The Rays made three other roster moves on Friday: outfielder Justin Ruggiano's contract was selected from Triple-A Durham, right-hander Rob Delaney was optioned to Durham and infielder Dan Johnson was designated for assignment.
Howell, 28, led the Majors with a combined 13 wins as a reliever in the 2008-09 seasons. He's 13-6 with a 2.38 ERA in 156 innings since moving to the bullpen in '08.
Howell got his feet wet in Friday night's 5-3 loss to Florida. He entered the game in the sixth and would have had an immaculate frame had Ben Zobrist not booted a ground ball.
"I had a lot going on in my head, man," Howell said. "But at the same time, I just wanted to throw strikes. I had a tough first two pitches. I just had a tough time not thinking. After that, I couldn't tell you a sequence that I did. But I'll get that down next time. ... It's not as fun when you lose, but it's still a great time, man."
Howell said his shoulder felt great.
"I still have a little adrenaline, so I think I'll know tomorrow morning where I'm at," Howell said. "I think that's definitely a good sign that I feel good right now, but it's one of those things [where] the next day tells you a lot more."
While Howell was used Friday night, Rays manager Joe Maddon said there is no reason to try to hide how they intend to use him because other teams will "pick up on it anyway."
Howell understands his use will initially be somewhat restricted.
"I think they're going to be really careful," Howell said. "They'll pitch me, give me a day off. Pitch me, give me a day off. Possibility of getting four outs and giving me a day off. I'm not necessarily cut down to one inning. I could go more than that. But I'm sure I won't be going back-to-back for the first week or two."
Howell now wears No. 74, switching from No. 39 as a tribute to Guy Dubets, Howell's pitching coach since age 11. Dubets, 52, passed away on Mother's Day in Carmel, Calif., from diabetes. No. 74 represents his initials, "G" is the seventh letter and "D" is the fourth."
Ruggiano, 28, posted very strong numbers with the Bulls: six home runs, 30 RBIs, as many doubles as steals (11) and a .308/388/.521 line.
In the past, Ruggiano has shown frustration about not already being in the Major Leagues. Maddon commended Ruggiano for keeping a positive attitude this time around despite getting taken off the 40-man roster, clearing waivers, and returning to Durham -- all while playing well.
"The biggest thing for me was trying to stay positive," Ruggiano said. "I had no idea this was coming. So I was more or less down there trying to set an example for other guys as well. ... To lead by example was probably the most important thing to me. Charlie [Montoyo, Durham's manager] is a great motivator. I can't say enough about him. He's the reason I'm still here."
Ruggiano will be used as an extra outfielder. One reason he was selected, aside from his performance, was the fact the Rays aren't afraid of him being used sparingly. The organization feels that Desmond Jennings and Brandon Guyer, both age 24, need to play every day.
Johnson, 31, has come up with several of the biggest hits in team history. But he just hasn't been able to get on track, going 9-for-78 (.115) this season. The emergence of Casey Kotchman made it difficult for Johnson to get playing time.
"He's not been way off, he's just been a little bit off," Maddon said. "He's the kind of guy who just needs to play on a regular basis to be productive. His swing is a high maintenance swing. ... He understood it. He was not visually upset. I know he didn't like it, but he was not adamant or visually disrespectful in any way. He got it. And he also understands that we would like to have him back."
To remain with the organization, Johnson needs to clear waivers and agree to return to Durham.
While the Rays appear to have just one first baseman now that Johnson is not with the team, Maddon pointed out that Sean Rodriguez, Elliot Johnson and Ben Zobrist can all play first base.
Delaney, 26, was recalled from Durham on May 8 and made three appearances, allowing three runs in his most recent.
"He needs to pitch more," Maddon said. "He did a good job. He had a couple of outings, one good, one not so good. But he just needs to go out there and pitch on more of a consistent basis. [He's a] good kid and I can see him coming back here."