Infield includes MVP candidates and a vet trying to bounce back

As the start of spring training fast approaches, we're breaking down the state of the Nationals roster, position by position. The series continues today with the infield ...

The Nationals' planned 2017 infield includes the league's reigning MVP runner-up, the league's reigning Rookie of the Year runner-up, one of the league's better all-around third basemen and a once-elite player who still hopes he can recapture his previous form and help lead his team deep into October for the first time.

Suffice it to say, this could wind up being an outstanding quartet - if everything falls into place. There is, of course, no guarantee that will actually happen, and so there are legitimate questions about all four players heading into the new season.

Ryan Zimmerman is perhaps the biggest question on the entire roster. Over the first eight full seasons of his career, he was a consistent offensive force, batting .284 with a .351 on-base percentage, .827 OPS and an average of 22 homers and 140 games played. Over the last three seasons, his production and playing time have plummeted: He has hit .242 with a .300 on-base percentage, .720 OPS and an average of 12 homers and only 90 games played.

What, then, is a reasonable expectation from the 32-year-old first baseman this season? It's anybody's guess. Zimmerman and the Nationals are hopeful that some small tweaks to his swing can help him elevate the ball better and turn many of his hard groundouts from 2016 into extra-base hits in 2017. But it would be irresponsible not to at least consider the possibility that Zimmerman never will be able to capture his prior form and that things will only continue to get worse moving forward.

It's also hard to say with any certainty what Daniel Murphy will produce at the plate this season. If he comes anywhere close to duplicating his .347/.390/.595 slash line from 2016, he'll cement himself as one of baseball's best hitters and not a one-year wonder. Some drop-off has to be expected, though, which could still be just fine in the end. Murphy was, after all, a career .288 hitter prior to last season. So even if he reverts to his old form, he's unlikely to fall off the table altogether.

Murphy worked hard to improve his defense at second base, and he'll need to continue working hard in the field this spring because he'll be paired with a new shortstop. Though Trea Turner grew up playing shortstop, he has only 31 2/3 innings of big league experience at the position because he was blocked there by Ian Desmond and Danny Espinosa.

With Desmond now playing in Denver and Espinosa now playing in Anaheim, the Nats were free to move Turner back to his natural position. But fair warning: The difference in his arm strength from the team's two previous shortstops will be noticeable. Then again, the difference in Turner's offensive production from Espinosa's numbers will be noticeable, as well, in a positive way.

The Nationals hope Turner can continue to rake at the plate the way he did during the second half of last season, and they hope the same will hold true for Anthony Rendon. After a sluggish start to his 2016 campaign, Rendon hit an impressive .287/.364/.494 with 18 homers and 80 RBIs over his final 124 games. (For comparison's sake, he hit .287/.351/.473 with 21 homers and 83 RBIs in 153 games in 2014, finishing fifth in MVP voting.)

Add Rendon's Gold Glove-quality defense, and the Nats have themselves one of the best all-around third basemen in the sport. All he needs to do is stay healthy and stay consistent.

The odds of the entire Nationals infield staying healthy all season are remote, which is why Stephen Drew should once again be a critical figure off the bench. Re-signed last month to a one-year deal, Drew will be asked to back up at second base, shortstop and third base, with perhaps even an occasional start at first base if needed. The Nats would love for the 33-year-old to stay healthy enough to get more than 165 plate appearances this time around.

Like Drew, Clint Robinson figures to again serve as a left-handed bat off the bench. The club's primary backup at first base, Robinson was a late-blooming revelation in 2015 (.272/.358/.424) but his production dropped in 2016 (.235/.305/.332) and he shockingly didn't record one extra-base hit in the season's second half. He'll need to do better if he wants to ensure his spot on the roster throughout 2017.

There may not be room on the opening day roster for Wilmer Difo, but the young infielder should find himself at Nationals Park at some point this year, probably for more than a cup of coffee. The organization has high hopes for the switch-hitter, who at worst profiles to be a utility infielder in the majors for many years.

If anybody falters along the way, the Nationals added two left-handed-hitting corner infielders to their 40-man roster this spring. Matt Skole is 27 and may never develop into the slugger the team envisioned when it drafted him in 2011, but he could provide some pop and the ability to play both first and third bases. Jose Marmolejos, meanwhile, gets his first chance to make an impression in big league camp after hitting .289/.370/.475 between Single-A Potomac and Double-A Harrisburg last year.

Infielders who have earned non-roster invitations to camp this spring include veteran and D.C. native Emmanuel Burriss, former Athletic, Angel and Giant Grant Green and Northern Virginia native and former Orioles first-round pick Brandon Snyder.