In 2003, in his fourth professional season, Brian Bruney split the year between AA and AAA, making his first venture to the top rung of the Diamondbacks' system. In 63.1 innings of work, Bruney posted a BB/9 of 4.41, a K/9 of 8.53, a K/BB of 1.94, and 0.14 HR/9.
This year, in his fourth season as a pitcher, Mike Dunn split the year between AA and AAA, marking his first venture to the top rung of the Yankees' system. In 73.1 innings of work, Dunn posted a BB/9 of 5.65, a K/9 of 12.15, a K/BB of 2.15, and 0.50 HR/9.
There are some differences between the two pitchers in the seasons in question. Bruney was drafted out of high school and was 21 in 2003. His 2003 season was pretty much an even split between the two levels (31.1 IP in AA, 32.0 in AAA). Mike Dunn was drafted out of community college and spent his first season plus as a professional playing the outfield before converting to the mound. He is 24 this season and pitched the bulk of his innings (53.1) at AA.
As I alluded to last week in our preview of September call-ups, Dunn's propensity for issuing free passes is a cause for concern. While he certainly won't keep up at his current MLB pace of 27 per 9, it isn't unreasonable to think that someone who's walked four per nine in his minor league career will do worse than that in the Majors. Some of that will be offset by his knack for striking batters out, but again, one can't expect him to duplicate his minor league rates in the Majors.
I'm certainly not trying write off Mike Dunn after two ugly Major League appearances. One can't underestimate the nerves involved in making his Major League and Yankee Stadium debuts. Dunn is still relatively new to being a full time pitcher, so he's very much an unfinished product. Hard throwing lefties are hard to come by, and he will be given every opportunity to succeeed.
Dunn is likely to spend most of next season at AAA, where I'm sure that reducing his walk rate will be the primary objective given to him by the organization. Hopefully he'll be able to draw on his month of Big League experience as he tries to make that improvment. If Dunn can develop into an effective Major League reliever he would give the Yankees a weapon that few bullpens have.
In the meantime, things are going so well for the Yankees at present that I've been reduced to nit picking about the walk rates of September call-ups.