While the Sox came into Tuesday night's game against Oakland with a 22-19 record, their Pythagorean won loss record is the exact opposite at 19-22. The Sox have been outscored 168-182 despite their winning record.
If you break it down by innings it looks like the Sox have started games slow and ended them worse:
Innings 1-3: 41-57
Innings 4-6: 69-50
Innings 7-9: 54-71
Now Jenks has actually pitched pretty well this year, so most of that damage has been done in the seventh and eighth. In those two innings the Sox have been outscored 55-39.
The Sox did blow a couple of late inning leads against the Cubs, but most of this damage was done by letting a couple games they were already losing get out of hand.
Middle relief is still a problem, but I think it is one of the easier ones a team can fix. The Sox have internal options and can always make a deal if things don't improve.
I think the quickest way to make the bullpen better would be to send Sisco down to the minors. His mechanics look horrible, he can't throw strikes, and he has one of the more pathetic change-up deliveries I have ever seen. He actually slows his arm motion down to throw the change as if he was a little leaguer believing a change-up just means throwing the ball slow.
He has a strong arm, but I doubt he ever gets his act together to become an effective pitcher.