General manager Jack Zduriencik could still add some veteran pitching through free agency or trade. But at the moment, five weeks before the start of Spring Training, Seattle's returning rotation consists of Felix Hernandez and Hisashi Iwakuma, plus youngsters Beavan, Erasmo Ramirez and Hector Noesi.
Former Tigers starter Jeremy Bonderman signed a Minor League deal with an invitation to camp, but he is coming off Tommy John surgery and hasn't pitched in the Majors since 2010.
Beyond that, the leading candidates are the touted prospects -- Hultzen, Paxton, Taijuan Walker and Brandon Maurer -- all of whom figure to get invitations to Spring Training next month.
Unless Zduriencik adds several veterans, it appears Beavan again will be in the thick of things this coming season after starting 26 games last year. At times during the 2012 campaign, Beavan showed an inability to limit big innings and struggled to keep his spot in the rotation, spending a month in Triple-A Tacoma in midseason to help with that process.
But at other times, the 6-foot-7 Texan made the most of his excellent fastball command, keeping opponents off balance and his own team in games well enough to finish the season 11-11 with a 4.43 ERA.
The stint with Tacoma came after a couple of poor outings. But after returning to the big league club, Beavan was far more effective, going 8-5 with a 3.40 ERA over his last 14 starts, including seven when he allowed two runs or less.
"I think, for the most part, I handled myself well enough up here," Beavan said at season's end. "Obviously, I want to do a lot better. I'm not satisfied where I'm at right now, but I learned a lot. So if I look at it in the whole picture of how the season went, I think it went pretty good."
Beavan, who had his first taste of the Majors with a July callup in 2011, has always relied on his fastball as his primary pitch. Although it's not a burner, his ability to hit spots in the low-90s has been his bread and butter.
He set a club record for the fewest walks per nine innings at 1.42, second in the Majors last year behind Bartolo Colon of the A's. His 10 starts without a walk were the most in the American League. But when he has difficulty locating the fastball, he's gotten into trouble.
Part of Beavan's struggle last season was his inability to fix problems with his slider, which has been one of his go-to offspeed pitches. Essentially, Beavan had become a fastball pitcher with no reliable alternative to keep batters off-balance.
When he was demoted to Tacoma, he was able to work on both his slider and curveball with Rainiers pitching coach Dwight Bernard in a low-pressure atmosphere.
"That's about all I worked on, throwing my slider and curve down there," Beavan said. "Just getting a feel for what I need to do to be successful with getting the break and finding the arm slot for those pitches. I think changing the grip on some on my pitches helped a lot, but I think also, just finding the arm slot with experience.
"Gaining the confidence, what I needed to tell myself was to stay on top of pitches better instead of getting around them and having them side spinning there and really getting that depth."
Beavan also sees spending almost an entire season in the Majors as a plus that will aide him this coming year. Having the right mindset when facing the best hitters in the game is what separates the elite from the regular pitchers, Beavan said. Confidence from throwing against the likes of Albert Pujols and Mike Trout is something to add to his arsenal.
The last piece to the puzzle for Beavan is a changeup.
"That's something that I really want to work this offseason because I look at some of the better pitchers in the game these days and they've all got good changeups," he said. "That just makes their job that much easier out there if something else isn't working.
"That's what I'm going to work on and come into Spring Training, hopefully ready to utilize that pitch and just get better with it."
And if Beavan can field a more complete repertoire of pitches to go with his excellent fastball command, the Mariners may in turn have a more complete package of starters when pitchers and catchers report on Feb. 12.