History: Coghlan vs. McCutchen 1.5 years later

Remember this argument?

Andrew McCutchen, congratulations, you’re the Marlin Maniac’s NL Rookie of the Year!

That set off a firestorm of debate on this site, in part because everyone knew that hometown favorite Chris Coghlan would have a hard time winning it playing for the unpublicized Marlins. Of course, McCutchen did not win and Coghlan ultimately did win the 2009 National League Rookie of the Year award, giving Coghlan some well-earned respect and snubbing a player whom I felt was more deserving of the award. In the resulting discussion, commenter Jorge Costales asked me this question (and I must once again commend him for having polite discourse with me as compared to one particular commentor on that same post):

Question: If your were a GM [for a normal team with budgetary constraints], which would you prefer?

Here was my response:

I think Chris Coghlan could be something like 5-6 runs better on offense. I don’t think Chris Coghlan is a good defensive outfielder (he might be average at some point in the next few years, if he sticks at the position), while I think McCutchen is an average to good defensive center fielder. If they both have the same playing time, I would choose McCutchen is I were a GM, because CF is harder to fill than LF. If Coghlan is a slightly below average 2B, the argument is much better for Coghlan. But as a below average or even average left fielder, he would need more bat to make up for the position scarcity/difficulty.

Jorge later said this in response:

So let’s talk probabilities. I submit that there is a higher probability that McCutchen’s career will not see him develop into a quality MLB player as opposed to Coghlan. Rookies who average .388 over a 2 month span — sorry, but especially over the final 2 months of the season — are the real deal.

A few years later, it turns out I was right (which takes nothing away from Jorge, who was making a sound argument, even if he missed the problem with Coghlan’s fluky BABIP). I decided that McCutchen would be the better player going forward, possibly offensively and certainly defensively, and I feel as if I nailed that prediction.

The hitting stats show a clear advantage for McCutchen, while his advantage in playing time over Coghlan, who lost 200-plus PA due to a torn meniscus, contributes to to McCutchen’s advantage in WAR. Over a little less than a season and a half more, Coghlan has been simply outclassed by McCutchen in almost every way. While Coghlan has struggled to play decently at the plate since his award-winning campaign, McCutchen has been scarily consistent throughout his entire career, and is doing so at a younger age.

Why McCutchen should have come out better

Take a look at those 2009 seasons by both players in terms of the “Four Factors” of success (really, I’m going to list five factors).

From this set of numbers you can clearly see where Coghlan and McCutchen outdid each other. Coghlan did a superior job in terms of strikeout rate and BABIP, while McCutchen bettered him in both power and walk rate. The important aspect in the question of which player would become better in the future is which of these statistics would be more predictive of future performance. Luckily, we have an idea of when these numbers generally become significant in determining true talent going forward. From Baseball Prospectus’s Derek Carty’s (my boss over there) recent article on when hitter stats stabilize, here are when some of the stats related to these numbers become about 50 percent predictive of future talent.

Here is Derek himself on how to read this chart:

Here are the results of running these tests for a number of stats. The following table has the stat in the first column, the denominator used in the second, how many units of that denominator before it stabilizes in the third, and approximately how many years that translates to in the fourth.To read the “Stabilizes” column—the one we most care about—we would say, “Strikeout rate, defined as K/(PA-IBB-HBP), stabilizes after 100 PA-IBB-HBP.”The “Years” column is for a league-average player (assuming 650 PA is one full season) and will sometimes vary significantly from player to player. It’s there as a quick-and-dirty way to make comparisons between stats since they’re all using different denominators. This allows us to say, “OK, strikeout rate takes about one-fifth of a year to stabilize, but singles rate takes over two years.”

What does this tell us about Coghlan and McCutchen’s 2009 seasons? Each of their strikeout rates, walk rates, and home run rates should have been established fairly early in their careers, with a point of halfway regression at around one fifth to one third of a season. This means that we would expect somewhere in between what we saw in the 2009 season and the league average going forward in both their careers. What we ended up seeing was a mixed bag. Coghlan’s strikeout rate jumped while McCutchen’s remained very similar. Coghlan’s walk rate diminished, currently down to 7.4 percent for the 2011 season, while McCutchen’s has remained solidly static. In terms of home runs, both players are hitting them out at 2009 paces, with McCutchen showing some slightly improvement.

The other two stats were the most variable, with BABIP taking almost two and a half seasons (!) to reach a 50 percent regression mark. Doubles and triples rate also is considered to take a long time to stabilize. How have the two players done in both categories since 2009?

So far, McCutchen has done a decent job maintaining both his BABIP and his doubles/triples rate, while Coghlan’s rates have also taken a tumble. Admittedly, it was much more likely to see Coghlan take a significant fall in BABIP given his .365 mark and the .298 average in 2009, but to drop to .306 after the 2009 season is probably overstating it as well. His career BABIP sits at a cool .332, and that number sounds very indicative of his talent. McCutchen, on the other hand, was able to sustain his strong BABIP mark and doubles rates just enough to make his decent power gains seem signficant. In other words, his game has been consistently good throughout his career.

Injuries and positions

So far, it is clear who the better player was the last few seasons. However, now the two have a direct chance at competing, given that they will both be playing center field in the near future. The numbers are mixed for McCutchen, who rated poorly in all the major defensive statistics but was scouted as an at least average defensive center fielder. It is likely that the truth is somewhere in between average to decently below average. Coghlan, on the other hand, has suffered no egregious problems moving to center field, though he has not necessarily looked great there either. The current offensive difference between the two hitters is great enough that McCutchen would still be comfortably in the lead even if Coghlan turned out to be better at center field than any of us thought, but it would certainly help Coghlan’s case to improve at the position.

In addition, playing time and injury have played a significant role in this comparison. Both players have played healthy when on the field, but Coghlan lost a good 40 percent of his 2010 season to a torn meniscus, and it may be possible that he is still recovering from problems regarding that. We should indeed give these two more time, but I think at this point you have to consider that McCutchen was the better player coming out of that season.