PEORIA, Ariz. — Scott Baker has been the ace of a playoff-bound team. He’s been an opening-day starter, and deemed good enough to warrant a four-year contract extension.

But now Baker is in that murky netherworld found in every spring-training venue every single season. Nearly two years removed from Tommy John elbow surgery that brought his flourishing career to a screeching halt in April of 2012, Baker could be a huge find for a Mariners rotation that needs one.

That requires, of course, a return to health by Baker, who believes he is ready, at age 32, to resume the path that helped him go 63-48 for the Twins before his operation. The Mariners hedged their bet, offering Baker a minor-league contract that will pay a $1 million guarantee if he makes the team, with a chance to earn another $3.5 million.

“I really felt, after five or six years, I kind of started to figure it out a little bit,” Baker said. “I felt I had a really good feel of how to pitch, and unfortunately, I was having probably the best first half of my career in 2011 before the elbow really started to bark. So I don’t think I’ve forgotten any of that. If I’m healthy, then I really feel good about my chances of having some success.”

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The phrase “if I’m healthy” is the crux of the matter, of course. In a rotation truncated by two aces at the top (Felix Hernandez and Hisashi Iwakuma), and probably two youngsters on the bottom (Taijuan Walker and James Paxton), there’s a spot wide open in the middle.

The Mariners could still sign Ervin Santana, the best free-agent arm still on the market. But if not, Baker will be a strong contender to crack the rotation in a battle that could be extended into the early part of the season because of Iwakuma’s finger injury.

So far, so good. Baker, a 6-foot-4, 215-pound right-hander, threw his first session of live batting practice Friday and all went well. He says he’s felt good all spring, noting that Tommy John recipients traditionally need two years to return to form.

“I feel like I’m finally over that hump,’’ he said. “The elbow is kind of a non-issue right now.”

Baker was hoping it would be a non-issue last year, and so did the Cubs, who signed him to a one-year, $5.5 million contract. They were gambling that Baker would be pitching soon enough to help them in 2013 and perhaps serve as a trade-deadline chip. But in his first start of spring training, Baker was battered by Oakland, experiencing a strained flexor muscle that wiped out most of his season.

“It was definitely frustrating, because I came into camp feeling pretty good,” he said.

Instead, it was back to the rigors of rehab for Baker until he finally made it back to the Cubs for three September starts. Those went well enough — he gave up just nine hits and six runs in 15 innings, with six strikeouts and four walks — that Baker was in demand this past winter as a free agent.

“It helped me immensely as far as going into the offseason knowing I had fully recovered and made a major-league start and did pretty well with them,’’ Baker said. “That definitely gave me some peace of mind going into the offseason.”

The Mariners, Baker said, struck him as the perfect spot, one with both a potential opening and what he saw as a competitive upside. His main competition in camp appears to be Erasmo Ramirez, although the situation is fluid beyond Hernandez and Iwakuma – assuming the latter recovers quickly from his finger injury.

“Probably selfishly, I feel there’s a good opportunity here for me to regain the pre-surgery form,’’ Baker said. “As good as anywhere. Of course, it doesn’t hurt at this point in my career I can be on a team that I feel potentially has a chance to win. If you look at the team as a whole, I think they’ve made some great additions. I want to be a part of a situation that has a chance to make the playoffs. Because I’ve been there, and it’s a lot of fun.”

The Mariners’ playoff hopes would be enhanced if they can solidify their rotation. Manager Lloyd McClendon has liked what he’s seen so far from Baker, but he wants to see how all the candidates do in game situations.

“I know this: You run them out there, they’ll either step up or eliminate themselves,’’ McClendon said. “I’m anxious to get it going and get in competition. You look at (Baker’s) track record, it’s pretty good. It’s just a matter of whether or not he’s healthy. Can he get back to the level he was?”

Baker is banking on it.

“This April will be two years (since surgery), and my elbow feels as good as it ever has,” he said.

Larry Stone: 206-464-3146 or On Twitter @StoneLarry