After the excellent rookie debuts of middle relievers Jonathan Broxton and Joel Zumaya, I am looking for some pitchers who could possibly fill that role this year. In mixed leagues, this is a pitcher who you swap in after a starter pitches in order to control the innings-pitched requirements. In AL- and NL-only leagues, these are the middle relievers you'd rather have than the #4 starter on the Royals or Reds.
One player who may fill this role this season is Giants middle reliever Brian Wilson. He doesn't hold quite the pedigree that Zumaya or Broxton had, but he is considered a future closer candidate. I'm a little leary given his poor 2006 debut (23K/21BB in 30 IP) and unimpressive AAA stats - 30 IP, 31K and 15 BB, but he is considered a possible future closer. In a bullpen with Armando Benitez, that counts more than the less-than-impressive stats.
The Dodgers have another fire-balling middle reliever named "Jonathan" in the minors who may follow Broxton this year - Jonathan Meloan. He struck out 91 across 52 minor league innings in 2006. He finshed at AA where he k'ed 23 in 10.2 IPs. More dramatically stated, that would be 23 strikeouts out of the 32 outs recorded. 72%! He is worth watching.