The veteran reliever, who celebrated career save No. 200 with Oakland in May, posted a 2.84 ERA over his first 19 appearances this season and subsequently found himself garnering save opportunities, but he went 0-2 with two blown saves and a 19.50 ERA and .452 opponents' batting average over his last seven outings.
Those numbers, along with a minor right ankle injury, led manager Bob Melvin to limit Fuentes' appearances. Fuentes made only two in his final 18 days, before the A's designated him to make room on the roster for Bartolo Colon, who was reinstated from the disabled list to start Tuesday against the Red Sox.
With Fuentes gone, the A's are afforded the chance to showcase younger left-handed relievers Sean Doolittle and Jordan Norberto, along with southpaw Jerry Blevins, and in time, Triple-A hurler Pedro Figueroa.
"I'm not really that surprised," Fuentes said. "It's just not really a good fit for me right now. It's unfortunate. It wasn't for lack of preparation. I was just pitching inconsistently, and it put Bob and the upper management in a tough situation, because they're trying to develop some guys and they can't wait for me forever. I think it's best for everybody involved. It gives me a chance to go somewhere and pitch.
"I don't think anything serious mechanically was going on. Just wasn't making quality pitches, falling behind in counts -- typical reasons why guys don't pitch well. I think the lack of work was a part of that, but also, when I did have the opportunities to pitch, I didn't pitch well."
"We just have some left-handers that are pitching in some more prominent roles now," Melvin said. "We need to look at some other guys and move them up in more prominent roles, and therefore that was the move we had to make."
If he isn't claimed off waivers, the A's have 10 days to trade Fuentes or release him outright. He had already been considered a trade candidate, so Oakland could potentially still go that route, though his value has diminished. Fuentes, making $5 million as part of a two-year contract this season, had a $6.5 million option for 2013 with a $500,000 buyout.
The 36-year-old has pitched for five teams in his 12-year career and has four All-Star appearances under his belt. His time in Oakland, though remembered by some for his 2010 rift with then-manager Bob Geren over a lack of communication, brought about several pivotal relationships with some of the club's younger pitchers.
This year, in particular, it was newly named All-Star rookie Ryan Cook who took to Fuentes' guidance.
"Words don't even describe how I feel about him," Cook said earlier this season. "He's been a big help to me, in helping me prepare, getting myself ready for any role. He's one of the first ones here every day getting his work in. The way he carries himself, just the way he goes about his business, the confidence he exudes and just the sure way to handle yourself in all situations, whether it be good, bad or ugly, it's all something I've taken in."
Via Twitter on Tuesday, Cook said, "I want to thank Brian Fuentes for the impact he has had on me not only as a player but as a man, all of which he may not even be aware of. Incredible player and even better person."
Said Andrew Carignan, also on Twitter: "Sad day in the clubhouse seeing [Fuentes] pack up. Couldn't ask for a better veteran for us [youngsters]. Thanks, Tito."
Fuentes was seen saying goodbye to several of his teammates before departing the clubhouse on Tuesday, and it was their words that brought him comfort, he said.
"I was shown the right way to do it, and I want to instill that on those guys," he said. "A lot of them have come up and said, 'Thank you,' and that made me feel better than anything."
"This is a guy who not only gave us contributions on the field, but in some places you don't see in the clubhouse and provided a leadership job for some of the younger guys in the bullpen, how to go about your business the right way," Melvin said.