Monday, October 19, 2015

How Good Were The 2015 Astros?

The Astros just ended a memorable run, a couple series before the ultimate prize. They snuck into the playoffs by winning the 2nd Wild Card by one game, finishing 86-76, the worst record for 2nd Wild Card since the new format was introduced. Almost no one saw this coming, and it would be easy to say they overachieved, and will need to get significantly better to maintain success.

Is this true though? Looking deeper at the underlying stats paints a much different picture, and bodes well for the future.

Just looking at Pythagorean Record, which takes basic runs scored and runs allowed to determine expected won loss records, the Astros should have finished 93-69. There is a lot of evidence to indicate Pythagorean Record is a better predictor of future performance than actual record. But there is an even deeper look, which paints an even better picture.

Fangraphs calls it BaseRuns. Baseball Prospectus calls it 2nd and 3rd Order Winning Percentage. I'm sure the inputs differ slightly, but they are both methods to strip away sequencing and clutch performance, which have almost no predictive power, to get to an expected won loss record based on underlying stats. Both methods agree the Astros were something close to a 97 win team.

In other words, the Astros hit and pitched like a 97 win team. So, how did they only win 86? They finished 29th of 30 in "Clutch" hitting and 28th in pitching in "Clutch".  I'm sure none of us can remember a time the Astros were "unclutch," can we?

But sequencing and clutch has been shown over and over to be, essentially, random. Good clutch teams one year become bad clutch teams the next, and vice versa.

In August of last year, the Cubs were under-performing their BaseRuns record by 8 games. Dave Cameron looked at the history of teams which under performed by a similar amount on JABO. He found
On average, these 11 teams underperformed their BaseRuns expectation by 53 points of winning percentage, the same mark as the Cubs are underperforming this year. Their overall winning percentage improved by 38 points in the next season, meaning that their record the next year came pretty close to their expected record in the prior season. Ten of the 11 teams improved their record in the next season. This is the kind of thing that is often referred to as regression toward the mean.   
Even if all the Astros do this offseason is bring back who they had, they should improve based on better distribution of events. But no one really expects them to stand pat. They have money to spend, prospects to call up, and maybe even some growth from the young players. But that BaseRuns numbers should give us a lot of optimism. Because they aren't really adding to a 86 win team. They are adding to a team that performed like a 98 team win in 2015, and could be on the verge of creating a juggernaut.