Spring training camps will open this week across Florida and Arizona, though a small army of free agents remain unsigned, including several excellent players. At the moment 21 of our top 50 free agents are unsigned, including six of the top 10. It's tough out there for a free agent.

Playing connect the dots between free agents and teams is easy and fun. The Red Sox should sign J.D. Martinez. The Twins and Brewers should sign Alex Cobb and Lance Lynn, in either order. The Yankees should sign Mike Moustakas. The Cardinals should sign Greg Holland. The Mets should sign Ubaldo Jimenez.

Wait, what?

Yes, the Mets should sign Ubaldo Jimenez. He is coming off a miserable season with the Orioles (6.81 ERA in 142 2/3 innings) and doesn't rank among our top 50 free agents, because duh. Ubaldo to the Mets still strikes me as an obvious free agent match. No, Jimenez won't put the Mets over the top, but he might be able to help this season, for a few reasons.

Don't laugh, Ubaldo Jimenez and the Mets are a good match for each other. USATSI

He's going to come cheap

The Mets are notoriously cash-strapped. Their current payroll projects to be about $10 million less than last season, and GM Sandy Alderson hasn't been shy about acknowledging that is the plan. Payroll will be down from last season.

Already this winter the Mets have committed $70 million across seven contract seasons to Todd Frazier, Anthony Swarzak, and Jay Bruce, and they're not expected to spend much more. Fortunately for them, Jimenez figures to come on a minor-league contract. He won't break the bank at all. A minor-league deal means no risk and a low base salary, and that's good news for the Mets.

The Mets need rotation depth

Let me rephrase: Every team needs rotation depth. The Mets are no exception. Consider their projected starting rotation:

Potential to be great? Absolutely. Syndergaard, Harvey, and Matz are all supremely talented. But staying healthy has been an issue for this group since they carried the Mets to the 2015 World Series. Wheeler is so desperate to stay healthy he spent the offseason injecting drugs into his stomach.

Yeah. The Mets may be eight starters deep in paper, but as they learned last season, that depth can disappear in a hurry. Ubaldo would be a low-cost depth option and wouldn't stand in the way of anyone should the top starters get healthy.

Jimenez is durable, if nothing else

Unlike many of the guys penciled into New York's rotation, Jimenez has done an excellent job avoiding the disabled list in his career. He's gone on the disabled list only twice in 12 seasons as a big leaguer:

Missed 15 days with a cut on his thumb in 2011.

Missed a month with an ankle sprain in 2014.

No notable arm injuries in his career. Jimenez has thrown fewer than 140 innings only once in the last 10 seasons and that was 2014, when the ankle sidelined him. There is value in taking the ball every fifth day.

He can pitch out of the bullpen

Jimenez has spent the majority of his career as a starter, though he is flexible enough to pitch in relief. He can shuttle back and forth between the rotation and bullpen seamlessly. Ubaldo made six relief appearances last year and four the year before. It's a role he can handle. So, if he's not needed in the rotation, the Mets can stick Jimenez in relief and use him as a long man.

Jimenez will reunite with Callaway

This is the big one. The Mets hired Mickey Callaway as their new manager this offseason, and Callaway was the Indians' pitching coach when Jimenez revived his career in 2013. That year he threw 182 2/3 innings with a 3.30 ERA (115 ERA+), and after the season he landed a four-year contract with Baltimore.

Callaway and Jimenez spoke to Paul Hoynes of Cleveland.com about their relationship during Ubaldo's resurgent 2013 season:

"When Mickey came to the Dominican (during the offseason), he told me he just wanted to be there for me," said Jimenez. "But he wasn't going to change anything. He just wanted to make me better. If I have bad mechanics, just try to be good with my bad mechanics." ... "I thought if we could just get Ubaldo in the strike zone and attacking hitters with the stuff he already had, that he would be good to go," said Callaway. "Watching his video during the off-season, I was saying, 'Man, his stuff is so good, all he has to do is get it over the plate.' "

The just turned 34-year-old Jimenez is the most enigmatic pitcher of his generation, but he is also so obviously talented, and Callaway was able to get through to him in 2013. Once the two were separated, Ubaldo's performance cratered. Reuniting them could be the key to turning Jimenez back into an effective big league pitcher. He doesn't have to be an ace. Just a depth arm who soaks up innings.

The Mets aren't expected to spend any more money this offseason, yet the need for a depth starter remains obvious. Jimenez has been pretty terrible the last few seasons, but he'll come cheap, he's durable, and there is at least some hope getting him back together with Callaway could be beneficial. And if it doesn't work, the Mets could cut ties with Ubaldo and move on easily.

There are still lots of free agents on the market as spring training opens -- lots of good free agents -- but one of the most obvious fits to me is Jimenez and the Mets. He fits their budget, fits their roster needs, and reuniting with Callaway may be the only opportunity Ubaldo can get his career back on track at this point.