A couple of intriguing non-roster invitees

Seemingly every year, there's at least one non-roster invitee who makes a major impression in spring training, and ends up surprising people and cracking the opening day roster.

Sometimes, it's a veteran who had been signed to a minor league deal with an invitation to big league spring training. Guys like Chad Tracy, who are looking to find their way back into the fold in the majors after an injury, time in Triple-A or a year playing abroad.

Other times, it's an under-the-radar minor leaguer, someone without much (if any) big league experience. Guys like Aaron Barrett, who impress coaches and scouts in spring and end up seeing their career take a major step forward.

This year, the Nationals have a roster that is filled with contributors from the 2014 campaign, and seemingly very few spots are open and up for competition in spring training.

One or possibly two bullpen jobs could be up for grabs. One, maybe two bench gigs could be there for the taking.

So who are the intriguing non-roster invitees to watch this spring? There are a handful of them, but I'll list a couple who I am keeping my eye on.

One is Mike Carp, the 28-year-old outfielder/first baseman who spent last year split between the Red Sox and Rangers.

Carp struggled out of the gate for Boston last season, and missed a solid chunk of time on the disabled list, which probably didn't help his cause. He was later designated for assignment and was claimed off waivers by Texas, but didn't perform well in limited time there, either. In total, Carp hit .175/.289/.230 with no homers and 13 RBIs in 149 plate appearances last season.

In 2013, however, Carp was a fairly major contributor for the World Series champion Red Sox. In 86 games, spanning 243 plate appearances, Carp hit .296/.362/.523, with nine homers and 43 RBIs.

He's mostly played first base and left field in his career, but can play right, as well, and has one career game at third base under his belt. He also toed the rubber one time for the Red Sox last season, so he could be an option as an emergency pitcher (if that holds any value to anyone).

Could he work his way into the mix as a reserve outfielder and backup to Ryan Zimmerman at first base? If he shows well and Nate McLouth struggles or experiences further injury issues, it sure is possible.

On the pitching side, I was tempted to list Matt Grace, the up-and-coming 26-year-old left-hander, who posted a 1.17 ERA between Double-A Harrisburg and Triple-A Syracuse last season. But with two lefties in Matt Thornton and Jerry Blevins already in the fold for this season, I have a hard time seeing Grace cracking the opening day bullpen this year.

Instead, I'll go with Heath Bell, despite his elevated numbers the last few seasons.

After leaving the Padres, where he excelled from 2007-11, pitching to a 2.53 ERA and saving 134 games, Bell has had issues replicating that success. He has a 4.91 ERA over the last three years, and has bounced from the Marlins to the Diamondbacks to the Rays to the Orioles to the Yankees.

The 37-year-old still feels that he has something left in the tank, and if he can find it, he could add another experienced right-handed arm to the Nats bullpen.

Bell is determined to come to camp in shape and ready to prove his value, and if he can do so, he'll work himself into the mix. The Nats still might end up adding another free agent reliever to a major league deal, but Bell certainly has a spot to win a job.