Why Is Bronson Arroyo Better?

During the Red Sox-Phillies game, Joe Buck and Tim McCarver, whose knowledge of the game of baseball is without question (they have none), they mentioned the trade over the offseason that sent Bronson Arroyo from the Boston Red Sox to the Cincinnati Reds in exchange for Wily Mo Pena. That got me to thinking about why Arroyo has improved from last year to this year.

At first, I thought the improvement of Arroyo to Cy Young caliber was a direct result of Arroyo leaving the DH behind in his move from the American League to the National League, but that does not seem to be the case. In fact, so far, Arroyo has faced a higher quality of batter this year (.755 OPS) than last year (.741 OPS).

The two main differences in Arroyo's statline come from his increased strikeout rate and his decreased walk rate, two of the three statistics a pitcher has complete control over. His K/9 has shot up from 4.6 to 6.3, an increase of 37% while his BB/9 has gone from 2.2 to 1.5, a decrease of 47%. Other than that, his stats are basically the same, although he has been less lucky this year, which is interesting considering his improvement.

UPDATE: A further look at Arroyo's stats may demonstrate that he has had better luck. Or maybe he is more effective. Either way, Arroyo's LOB% has drastically increased from 65.9% to 81.2%.