On Tuesday, Howell let the team down in a major way.
The left-hander gave up a two-run homer with two outs in the eighth to Matt Wieters that cost the Rays in a 4-2 loss. Tampa Bay fell back to four games behind the wild-card-leading Red Sox.
"It just makes you sick," Howell said.
"Everybody's got to contribute," manager Joe Maddon said. "That's a particular situation that I believe that he can do. So for us to get into the playoffs and then be successful there, that's the kind of situation he needs to work through.
"Kyle was not available tonight, so then all of a sudden things become a little bit different. J.P.'s been a rock for us in the past, and he's been doing pretty good work lately. Of course he's not very happy right now, but I have a lot of faith in him."
Howell rejoined the Rays in May after missing all of the 2010 season with a shoulder injury that eventually required surgery. He is healthy, and his velocity is fine, but his location and feel are off at times.
The two-run homer accounted for more runs than Howell had allowed in his previous 17 appearances combined. He had an 0.82 ERA in that 11-inning stretch that dated back to July 29.