"The last eight years of his career, though, which he spent on the Yankees, were not nearly as good as his first. Whether this is a product of his complacency after signing a big contract, or a result of the pressure of pitching in New York City, or just a natural result of his aging (after all, he didn't sign with the Yankees until he was 32), it's hard to say. It is clear that those Yankees years were not up to the standard that he set for himself in Baltimore, and that seems to be the main reason that some people don't remember him as being great."
That stuck in The Common Man's craw, and he started to wonder what, if anything, happened to Mussina during the move from The Charm City to The Big Apple. Now, The Common Man should preface this by saying that he is not a number cruncher by trade, and that some of the conclusions here may be rough. He leaves it to those with better resources and more time at their disposal (or just to the peanut gallery of armchair bloggers) to figure out if The Common Man is on to something here. All statistics were derived from that trustiest of trusty sites, baseballreference.com.
Here are Mussina's rate stats for his time as an Oriole and a Yankee:
Orioles ERA: 3.53
Yankees ERA: 3.88
Orioles K/9: 6.9
Yankees K/9: 6.2
Orioles BB/9: 2.1
Yankees BB/9: 1.8
Orioles HR/9: .94
Yankees HR/9: .96
As you'd expect, the raw data seems to indicate that Lar is right. Moose's ERA is a third of a run higher as a Yankee, and his declining strikeout and walk rates seem to indicate a pitcher who's compensating for a loss of velocity. In addition, the relative stability of his homerun rate could be a result of moving from a good homerun park (Oriole Park at Camden Yards) to a more difficult one (Yankee Stadium). Like most pitchers, as he aged Mike Mussina had to survive by pitching more to contact.
And given the state of the Yankees defense, perhaps this was exactly the wrong time for Mussina to have to make this adjustment. In his prime, up the middle in Baltimore, Mussina had Ripkens (plural), Harold Reynolds, Mike Devereaux, Robbie Alomar, Brady Anderson, and Mike Bordick, all players with excellent defensive repuations. Meanwhile, as a Yankee, he's had Soriano, Jeter, Miguel Cairo, an aging Bernie Williams, Robinson Cano, Johnny Damon, and Melky Cabrera. Defense has not been a hallmark of the Yankees of late, and Mussina's shift in pitching strategy seemed destined to lead to more basehits.
Indeed, if one crunches the defensive numbers, Mussina's Orioles allowed a .293 average on balls in play, while his Yankees allowed a .298 batting average. As Mussina's strike out rate dropped, one would assume that this more porous defense would affect his overall performance even greater. And indeed Mussina gave up 8.5 hits/9 as an Oriole, but 9.1 as a Yankee. And given how many Baltimore singles may have ended up as New York gappers, perhaps it's not a stretch to say that the majority of Mussina's problems in New York were caused by the disappointing defense playing behind him, rather than the attrition of his ability (during which he maintained a respectable K/9).
The case is, of course, far from proven. There's significant noise in that data and a lot of logical leaps that The Common Man made. Perhaps as Mussina gets closer to his enshrinement in the Hall of Fame, others can do some of the heavier lifting, and demonstrate just how effective Moose remained in the Yankee years, and how deserving he is of baseball's highest honor. In the meantime, since it seems to bring you people back in droves (and The Common Man does love droves), here's Mike Mussina's Strat-o-Matic card from his fabled 1992 season (18-5, 2.54 ERA, 48 BB, 16 HR, 130 K in 241 IP, and a 157 ERA+):
As you can see, Mussina has a pronounced reverse platoon split. He allows fewer hits and less power to lefties (in his real season, lefties managed to hit just .220/.269/.280 off Moose, with just one homer in 459 plate appearances), has a strong ability to induce the double play (any grounder with an A next to it is a DP), and can go deep into games (8 innings without tiring). He even holds runners well, automatically decreasing their chances of stealing second by 15% (the hold -3 rating). In all, this is what The Common Man dreams about at night, when he thinks about the perfect pitcher. And only 23!