Who should the Rays add to the 40-man roster?

The Rays have until midnight to settle who will be on the 40-man roster, with the consequence that any player left unprotected could be drafted by another team, during the Rule 5 Draft in December.

It's common for a handful of teams to claim a player, but it's not necessarily common for a player to stick. A drafted player can be kept by the acquiring team only if that player makes the major league 25-man roster out of camp, and stays up all year.

Last season, three such players were acquired and kept through the Rule 5 process: catcher Adrian Nieto, and two pitchers. I keep it that simple because pitchers are the main focus of this draft, as it's easy to hide any arm a team truly likes in the bullpen. Nieto is the anomaly, a catcher who had the skills but missed significant playing time. The White Sox took the gamble of promoting him straight to the show, and the kid stuck, fulfilling the intention of the draft.

So who do the Rays need to protect?

Any team that has a catcher that can carry the bulk of playing time - like the White Sox had with Tyler Flowers, or the Royals having in Salvador Perez, or the Cardinals have in Yadier Molina, or the Blue Jays now have in Russell Martin. It's easy to stash a promising catcher behind a stalwart, so the first priority for the Rays will be protecting catching prospect Justin O'Conner.

Is he promising? Baseball America's recent No.3 ranked Rays prospect has a strikezone that's a work in progress, is capable in his receiving, more than capable with his defense and his lumber, but promising because of his arm. Any player that has a 7-grade anything in the minors and qualifies for the draft probably needs protected, and ‘Bustin has an 8-grade arm. It's the best, in all of the minors, and everyone knows it so he'll be protected.

Ryan Brett is another prospect with a 7-grade tool: his speed. The third round draft choice is limited to second base in terms of projection, but he has a bat that will play at the major league level and deserves top-five consideration on any Rays prospect list.

Mikie Mahtook has some a little more optimistic about the future than Brett. Mahtook has a solid set of tools and continues a steady development as another great defender in the Rays system. Coming off his first season at AAA, he didn't replicate his 25 steals from 2013, but his bat blossomed to where it should be, with a 125 wRC+ and .366 wOBA. That came with more power and more strikeouts, but he could really put it together in the very near future. He's not a piece we'd want to let go, as he'd easily stick with a National League club as an extra outfielder.

There's a few other possible bench players to discuss, and they're both outfielders for the Montgomery Biscuits. Supplemental first rounder Kes Carter carries no bat but plenty of defensive value, and seventeenth round choice Taylor Motter who has plenty of thump and saw a lot of time in spring training with the big league club. Motter had 16 longballs last season, and already five in the Venezuela winter league.

The only other lock in my mind is starting prospect Matt Andriese, who the Rays acquired last off-season from the padres as starting rotation depth. He's durable, a groundballer, and his stuff would play as a No. 5 if he were promoted today, with a chance to trend higher with a touch more development.

Among the rest of the pitchers to consider, Adam Liberatore has the upside. He limited Triple-A hitters to 58 base runners in 65 innings, with a sensational 34.8% K-rate, paired with a 6.1% walk rate, 1.66 ERA, and 1.65 FIP. You'd like to think the trade of Cesar Ramos clears a spot for Liberatore next season, but this front office is already off to a strange start.

New GM Matt Silverman's first move was signing Michael Kohn, a reliever with a suspect track record at the major league level, to a major league deal. Why now? Even if Kohn is another diamond in the rough that Jim Hickey plans on polishing into the next Rays success story, his deal demands a roster spot, further complicating other arms worth protecting.

For those other arms, I defer to Ian's coverage from yesterday:

I'm going to lump Jeff Ames, Grayson Garvin, and Merrill Kelly together. They're all guys who might do okay as the last man in a bullpen right now, but who the almost surely aren't ready to contribute at a high level in the majors. I don't think the Rays protect any of them, but I wouldn't be shocked to see them claimed. Ames is a first-round pick who has never pitched above high-A. The other two are closer to the majors but probably have lower ceilings.

I like the pedigree of Ames, I like the potential of Garvin, and I like the dependability of Kelly. I could see all three succeeding in a major league role sooner than later, and no room for them on the 40-man, which is a shame.

That's about it for the players eligible for this discussion. As a reminder, the barometer is either players signed at age 19 or older that have played in four seasons, or players signed at age 18 or younger that have played in five seasons. Any player that features in with the Rays for an extended look in spring training might be worth saving, like catcher Luke Maile, but as a 2012 draft choice he's safe.

Who are we missing that needs protected? And who needs to go to make that happen?

The Rays have until midnight to protect players, with four I've identified as must adds and only two slots available. That puts players like Cole Figueroa, Steve Geltz, and Brandon Guyer on high alert for the rest of the day, unless the front office can find a trade to clear roster space. Here's my full priority list, as things stand:

- Justin O'Conner
- Mikie Mahtook
- Ryan Brett
- Matt Andriese
- Adam Liberatore
- Jeff Ames
- Taylor Motter
- Grayson Garvin
- Merrill Kelly
- Kes Carter