And that's not even all of them.
Some are new to the organization. Others aren't. They all share a common thread.
"Maybe the one thing that we emphasize more than the average team probably is we look more for strike-throwers than pure stuff," said Farhan Zaidi, A's assistant general manager/director of baseball operations. "Not that there aren't other teams that don't do that, but it's really important for us when we believe that with a good defense and a good park to pitch in, that guys aren't putting runners on and beating themselves. So I think that's a bigger emphasis for us with guys than maybe the average team."
By placing great weight on this ability, the A's last spring landed Otero on a waiver claim from the Giants. The right-hander had toiled in the Minors for the better part of six years, with just 12 big league appearances to show during that time. By year's end, he had made 33 more for the A's.
Along the way, he allowed just six earned runs in 39 innings. He struck out 27 but, more important, walked only six to average 1.38 walks per nine innings. Only Boston's Koji Uehara (1.09) and future Hall of Famer Mariano Rivera (1.27) posted a better rate.
"He doesn't throw 95," said Zaidi, "but I think he is an example of a guy who maybe appeals to us more than other teams, and he was obviously pretty successful last year."
Oakland's bullpen issued just 154 walks on the year, fewest in the AL and second-fewest in the Majors only to St. Louis' 148. Its collective average of 2.92 walks per nine innings was the A's lowest mark since 1990 (2.70). Hitters reached base against them at just a .271 rate and hit a dismal .217.
Bob Melvin has never managed a better bullpen -- until now, perhaps. This one has the makings of an all-timer. It's that special.
"Pitching and defense will win you those close games, and that's what's going to put us on top," said Doolittle. "We expect to be one of the best bullpens in baseball. Hopefully, when it's all said and done, they're going to be talking about how good the A's bullpen was and not necessarily singling out one guy that had a great year. We want to be known as that lockdown group, and on that short list at the end of the season of the best bullpens in baseball."
Doolittle, a converted first baseman, has quickly groomed into one of the best lefties in the game. But he's no specialist -- his splits actually show he's fared slightly better vs. righties -- and that's not a bad thing. There's a reason he's one of five pitchers on the A's roster who can spell Johnson with an occasional save assignment.
Johnson, too, can handle both types well, thanks to an exceptional hard sinker ball that's resulted in hundreds of groundballs -- 120 in 2013, to be exact, which was good for fifth most in the AL. That's why the A's aren't so much concerned about his less-than-glamorous strikeout totals.
"I think, in this day and age, when there's been greater emphasis not just in roster construction, but in manager strategy on matching up, you don't want anyone that creates too much exposure one way or another," said Zaidi. "Every team now has a bench of guys that they're not afraid to bring in if the situation calls for it late in the game. That's something we've tried to do. We kind of like it when a specialist comes in against us late in the game, because we usually have someone off the bench well suited for the matchup. The flip side, when you're putting a pitching staff together, is you don't want anyone that's a one-trick pony or limited in matchups."
Melvin smiles when asked if this makes his job harder or easier.
"What it allows me to do is not tax these guys too much," he said. "During the course of the season there are times when you're winning a lot of games in a row, a lot of close ones in a row, and you're leaning on them more so than you want to, and then you have the stretches where you're not getting them in games and looking to give them an inning. To have guys that aren't so much specialists makes that a little bit easier to rotate it. We really don't have one guy down there, where you're saying, 'OK, he's going to match up for a hitter' like we have with some guys in the past."
Dramatic finishes are great, but you can't win without hard laborers like the A's employ. Oakland was 30-20 (.600) in one-run games last year, including 17-7 at home. Moreover, the club was 77-6 when leading after seven innings and 82-3 when holding the lead after eight.
"If you look at the style of baseball that we play, where our focus is on pitching, defense and timely hitting, that lends itself to a lot of close games," Doolittle said. "Over a long season, if you want to have success, you have to have depth down there. You can't just have your closer and a couple setup guys. Right now we have five guys with experience pitching in a setup role. Because we play so many close games it's even more important for us to have a deep bullpen with a lot of options that we do now."
"We're very focused on depth, which doesn't exactly make us unique," said Zaidi, "but it falls in line with what we do on the position player side. Even if we perceive ourselves to have a full seven-man bullpen, that's not going to stop us from going out and acquiring someone."
That's what the A's did just days ago, when claiming Savery off waivers from the Phillies.
"You could've made the case that we had seven, eight, nine guys already competing for spots," Zaidi said. "But we know that once the season starts you can just never have too many guys.
"At this time of year, I think when people are making their prognostications about teams, it's really focused on what the Opening Day roster is, but we know that over the course of the season we know that that probably matters less than people think right now."