Why PECOTA projections have been so improper in regards to the Cubs
Sam Miller
ShutESPN.comESPN baseball columnist/characteristic author
Former editor-in-chief of Baseball Prospectus
Co-author of “The Solely Rule Is It Has To Work”
Jesse Rogers
Shut
ESPN Workers AuthorJesse joined ESPN Chicago in September 2009 and covers the Chicago Cubs for ESPNChicago.com and ESPN Radio 1000.
Earlier than the 2019 season started, opinions on how the Chicago Cubs would rebound from a disappointing end to 2018 have been different — however one stood out from the remaining. PECOTA, Baseball Prospectus’ math-based system, pegged Chicago for 79 wins and a last-place end within the NL Central. The identical Cubs who had gained 90-plus video games in 5 consecutive seasons and have been coming off a 95-win season. As you possibly can think about, this didn’t go over properly within the Cubs clubhouse or all through the Windy Metropolis.
Now flash ahead a couple of months and the Cubs are sitting at 27-18 and on tempo for a 99-win season, a far cry from that 79-victory marketing campaign that PECOTA projected. So what offers? How may a projection system be this far off? Does this early-season success imply Chicago goes to outperform the formulation all yr or is a big-time pitching regression on the best way? We enlisted ESPN’s Sam Miller and Jesse Rogers to look into all of it.
The PECOTA prediction: Final place, NL Central
Why PECOTA was so low on the Cubs: This is what a group projection actually is: PECOTA runs particular person projections for each participant, primarily based totally on latest efficiency (weighted for a way latest) with some small changes for age. Then, it provides up what number of runs a lineup of these gamers “ought to” rating and what number of runs a workers of these pitchers “ought to” permit. This run differential is used to estimate the group’s report, since groups that rating extra runs than they permit are inclined to win extra video games than they lose.
Put that means, group projections are a lot much less controversial than we regard them as, and within the giant majority of circumstances — possibly 27 or 28 groups a yr — they don’t seem to be even stunning, plus or minus a few wins. PECOTA is just not a hot-take columnist or a fortune teller attempting to divine which nice participant will out of the blue flip unhealthy. It largely simply applies constant arithmetic to do what all of us do once we resolve which groups we like within the NL Central this yr. That is how, as an illustration, PECOTA projected the Cubs — who completed sixth within the NL in scoring in 2018, narrowly behind the 2 groups forward of them — to complete fourth in scoring this yr. The Cubs have been sixth the yr earlier than, in a digital tie with the 2 groups instantly above them. No Cub may complain an excessive amount of about that.
With that mentioned: There are some additional steps which are a bit extra interpretative, and people added as much as a stunning projection for the Cubs. One additional step is placing extra weight on some participant attributes (strikeout and stroll charges, particularly) over others. The thought is that Okay and BB charges (to simplify issues) are extra steady, much less influenced by luck or circumstances and extra predictive. Projections usually use ERA estimators (like FIP, or in PECOTA’s case, deserved run common) as an alternative of ERA to evaluate pitchers. To provide one instance, right here is Jon Lester’s efficiency over the previous two years:
2018: three.32 ERA, four.39 FIP
2017: four.33 ERA, four.10 FIP
PECOTA (which does not use FIP, however is philosophically extra aligned to it) thinks Lester is definitely the low-4s pitcher. It does not even actually see that three.32. So it projected a four.42 ERA for the 35-year-old in 2019.
That is not a controversial place to tackle a single pitcher. Most analysts, followers and fantasy managers do some calculation of this type when compelled to foretell the longer term. However the Cubs’ pitchers difficult it by virtually all outperforming their FIPs final yr. They have been, as a workers, second within the NL in ERA however 12th in FIP. That was the biggest hole between these two measures in baseball, and it accounts for about 80 runs of distinction in how PECOTA assesses the 2018 Cubs and what the standings mentioned.
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Moreover, as a result of the members of the Cubs’ workers are previous, PECOTA figured they have been extra prone to be getting worse of their careers than getting higher. Because of this PECOTA thought the Cubs would permit extra runs this yr than they did final yr.
The opposite additional step is attempting to estimate protection with some precision. For the Cubs projection, this confirmed up particularly in catcher framing. The Cubs, in response to Baseball Prospectus, have had very poor framers not too long ago, and PECOTA anticipated that might proceed. Most projection programs do not incorporate framing, which may have a considerable impact on a pitching workers. Because of this PECOTA thought the Cubs would permit extra runs than another projection programs did.
The underside line is that PECOTA anticipated the Cubs to principally have the identical offense that gained 95 video games final yr, and the identical behind-the-pitcher protection that gained 95 video games final yr, however a a lot worse pitching workers, even because it introduced most of final yr’s 95-win workers again. That is a reasonably daring take, centered totally on mediocre projections for Cole Hamels, Jon Lester, the bullpen and Willson Contreras’ framing skills. — Sam Miller
Why the Cubs have been so ticked off by that: This one is straightforward. When somebody — a lot much less a pc program or algorithm — states a participant is just too previous to carry out at a excessive stage, mentioned participant goes to push again on the maths that produced mentioned evaluation. That is human nature, so the Cubs took it personally. Even when historical past has proved PECOTA extra proper than improper, they felt you possibly can’t apply a formulation with out considering the person. Hamels in all probability summed it up finest when he defined that what made him and Lester particular within the first place continues to be going to make them particular even at 35. In different phrases, it is not about their stuff, it is about them. After all, Father Time has by no means misplaced, however we’re not speaking about two 40-somethings right here.
The Cubs additionally believed their workers may solely enhance contemplating each Yu Darvish and Tyler Chatwood gave them nothing a season in the past. With Hamels in tow for a full yr and a wholesome Darvish — even when he was simply common — the maths simply didn’t add as much as 79 wins. Regression was and is a chance, however that was a bit an excessive amount of to swallow for the Cubs. And so they mentioned so. — Jesse Rogers
What’s occurred since
The maths says: The Cubs’ pitching has been incredible. (Their catchers’ framing has not been, however regardless of.) Of the 9 Cubs pitchers who’ve thrown probably the most innings, all however one is pitching significantly better than his projected ERA:
Cubs pitchers vs. projected ERA
PitcherProjected ERAActual ERACole Hamels4.093.13Jose Quintana4.003.68Kyle Hendricks3.953.21Yu Darvish3.815.14Jon Lester4.422.09Tyler Chatwood4.972.96Steve Cishek3.952.45Brad Brach4.412.41Brandon Kintzler5.143.38
That is partly as a result of the Cubs’ pitchers are once more outperforming their peripherals, however the extra so as a result of they’re collectively pitching higher this yr than they did final. They’re on tempo to strike out 150 extra batters than they did final yr. Lester, to offer one instance, is placing out virtually two extra batters per 9 innings than he did final yr, whereas additionally strolling batters at a career-low fee. He’s, in reality, to date, having the very best yr of his profession.
PECOTA — which, once more, is principally averaging the previous to provide you with a projection — will virtually by no means undertaking a participant to have his finest yr, and particularly not a 35-year-old. It is just about unattainable for the system to spit out such a projection, restricted as it’s by the boundaries of the participant’s previous efficiency. It isn’t, in fact, in any respect unattainable for a 35-year-old to have a career-best yr, as a result of the previous isn’t any restriction on him. PECOTA largely leaves the surprises to shock us, they usually inevitably do. — Miller
The view from the ballpark: That is the place watching how issues develop turns into vital, and if the Cubs hadn’t bottomed out throughout their season-opening highway journey, maybe they might not have gotten the bounce they’ve skilled. The yr started with loads of walks, from their beginning workers in addition to their bullpen. The outcomes adopted go well with. The group got here residence with a 2-7 report earlier than ever stepping foot in Wrigley Area. However because the stress started to mount on the mound, the veteran starters took it upon themselves to cease the free passes. They mentioned as a lot publicly.
Maybe, that is the place PECOTA comes up brief as it will probably’t take note of the brains and fortitude age brings you. Hamels led the best way, occurring a 22-inning walk-less streak. Jose Quintana, Lester and Kyle Hendricks adopted go well with. These 4 pitchers have walked a complete of 45 batters all season over the course of 36 begins. Do the maths on that. They’re making the opposition earn it — to the purpose the place they do not care about giving up residence runs. Everybody offers up residence runs on this period, however the secret is making them solo photographs, not three-run jobs. The Cubs seized on that mantra and it has permeated the workers — with one exception. Darvish leads the league in walks, so it is no shock his ERA is 5.06 after Monday’s loss to the Phillies, through which he walked three. — Rogers
The place it goes from right here
The maths says: Effectively, look, projections could be actual jerks. One among their jerky habits is persisting of their assumptions a few group for some time, even when the group in query thinks it has whupped PECOTA. So, in the event you go to Baseball Prospectus, you will not discover PECOTA’s letter of apology. Moderately, it simply retains spitting out its forecasts, day after day, and every day it nonetheless principally distrusts the Cubs’ pitching workers. It nonetheless thinks they seem to be a .500 group, possibly barely worse. Its projected ERA for Jon Lester, going ahead, is simply barely higher than it was two months in the past: four.32.
2 Associated
In case you suppose that the system was at all times improper in regards to the Cubs, this should not hassle you. Solid it apart. It is acquired a bug. Who cares? In case you suppose that the system was on to one thing, with all that stuff in regards to the pitchers being previous and outperforming peripherals in a hard-to-repeat sort of means, then the unhealthy information for the Cubs is that six weeks of video games aren’t that predictive. As Jeff Sullivan, now of the Rays, wrote at FanGraphs, even first-half information, and first-half run differentials, do a a lot worse job of forecasting the second half than projections do.
However the excellent news for Cubs followers, no matter how significantly they take PECOTA’s concern, is that every one these Cubs wins are already within the financial institution. As we speak’s PECOTA projection would possibly suppose the Cubs are a .500 group going ahead, however a .500 group with a game-and-a-half lead and a 10-game head begin on .500. That is adequate to make the Cubs no less than co-equal favorites for the NL Central, and better-than-50 % bets to make the playoffs. Even PECOTA says so. — Miller
The view from the ballpark: That is the place it might be too simple to easily say PECOTA was improper and transfer on. Whether it is proper, it is very attainable the regression exhibits up within the second half when Hamels and Lester, for instance, have extra innings underneath their belts. Age is extra prone to “catch up” to a pitcher later within the yr versus in April, proper?
The opposite subject is how issues went down for the Cubs final season. Their second half confirmed warts of their offense that by no means appeared early within the season. It is a reminder group can actually have two seasons, earlier than and after the All-Star break. A month from now, all of us would possibly be capable to declare PECOTA lifeless improper — it seems to be that means now — however regression does not have to indicate up on day one. Time will inform the story. Even the Cubs have been pleasantly shocked by the beginning Lester had, for instance, so it is attainable some guys are over-performing. It is simply unlikely. — Rogers