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Wednesday, February 27, 2013
Mulligan ERA: Impact of awful starts

By AJ Mass

"Consistency is contrary to nature, contrary to life. The only completely consistent people are the dead."- Aldous Huxley

When it comes to evaluating fantasy players, we are far too easily deceived by consistency. That's because the human mind is far too willing to look for patterns in numbers, and when we see them start to emerge, we can't help ourselves. We are captivated by these patterns and often can't wait to give them more significance than they deserve.

Case in point: I'd like you to consider the stats from the following two pitchers over a random stretch of eight games selected from each hurler's 2012 season. Which pitcher would you rather have had in your fantasy rotation over this span of time?

I would think most people would be far more inclined to select Pitcher A and his consistent run of starts over the roller-coaster ride that Pitcher B put his owners through over his month-plus of outings. However, if you take a look at the actual impact on fantasy standings for both pitchers across the standard pitching categories, you'll see that the difference between the two hurlers was not all that great during those periods, with Pitcher B coming just three strikeouts shy of winning three categories.

It's pretty clear that it would not have taken much to tip the scales in either direction over such a small span of time, and this comparison was made over a minimal sample size, one that just happened to have two of Dempster's worst outings of the season (including his first start with the Rangers following his trade from the Cubs). When all was said and done at the end of the season, taken as a whole, both pitchers ended up with identical ERAs. Still, if we were to give a "mulligan" to both pitchers and remove their worst three starts from the equation, the resulting comparison of their 2012 ERA yields quite a different impression of the two pitchers.

Simply put, a pitcher's "mulligan ERA" shows what a pitcher's ERA would look like if we were to ignore each player's three worst outings of the season as determined by Game Score, a statistic developed by Bill James. Obviously, this will result in a better ERA for all pitchers. However, as you can see from our above example, the difference is greater for some pitchers than others.

This can be an extremely useful indicator for owners who play in weekly leagues. In a rotisserie league, all that really matters are the end-of-season statistics, and in that case Sabathia and Dempster had the same fantasy impact in terms of ERA.

But in a head-to-head league, which pitcher is more appealing: the one who has a 90 percent chance of giving you a 2.49 ERA or the one with a 90 percent chance of giving you a 3.11 ERA? Sure, both pitchers could blow up in any given week, but over the long haul, Dempster helped you far more when he was "on" than he hurt you when he was not.

One reason for this is the fact that managers will often leave their better pitchers out there longer during a bad start, in hopes they'll turn it around. Those aces will get that extra leeway to try to pitch themselves out of a jam even when they don't seem to have their best stuff working for them.

As a result, when good pitchers blow up, their ERA often takes a monumental hit and might not recover for many starts, if at all. Pitchers who haven't earned the complete confidence of their manager will get the quick hook and not see as much of an impact from their darkest days on the mound.

Mulligan ERA is a way to see which pitchers truly were the most consistent over the course of the season. A low difference between the actual ERA and the mulligan ERA means the pitcher was more consistent; his worst starts and his typical starts were close to the same. In this case, the consistency we see is not of the "foolish" variety, but rather one that you can expect to continue into the coming season, for better or worse:

There is one other factor to consider, and it's what I'm calling "balance." Some pitchers had bad outings that were so out of line with the rest of their 2012 body of work, these few bumps in the road had a profound effect on how their seasons may have been perceived. Balance is determined by also giving a pitcher a "mulligan" on his three best starts and seeing if removing his best and worst truly comes out in the wash.

Here is a list of pitchers who had the biggest gap between their worst days and their best days. Perhaps we should give these guys even more credit when evaluating them for the 2013 season. If you're looking for sleepers, this would be a good place to start.

And here is the complete list of mulligan ERA and balance numbers for all pitchers who started at least 20 games and threw at least 162 innings in the 2012 season: