Seager, Matz among rookies set to play big roles for contenders in 2016

The 2015 rookie class was historically great. Several first-year players contributed to contending teams in a big way too, including Kris Bryant and Carlos Correa, the two Rookies of the Year. I have to imagine it'll be a long time before we see a rookie class like that again.

In 2016, more rookies will surely impact the postseason races, and some will be in position to do so right from Opening Day. MLB clubs are relying on young players more and more with each passing year, so much so that teams put rookies at important positions right away. They don't ease them into things anymore.

Let's look at some of those rookies set to play important roles for contending teams in 2016. For the purposes of this post, we're going ignore imports like Kenta Maeda (Dodgers), Byung Ho Park (Twins) and Hyun Soo Kim (Orioles). Yes, they are technically rookies, but they're also veterans with years of pro experience overseas. That's much different than being a young 20-something trying to cut your teeth at the highest level for the first time.

CF Byron Buxton & CF Max Kepler, Minnesota Twins

Buxton ZiPS Projection: .266/.310/.405 and 2.9 WAR
Kepler ZiPS Projection: .252/.310/.396 and 0.6 WAR
Competition: Joe Benson, Darin Mastroianni, Danny Santana, Ryan Sweeney

Both Buxton and Kepler made their MLB debuts last season, and the Twins believe in both enough that they traded incumbent center fielder Aaron Hicks earlier this offseason. They'll have some others competing for the center-field job for show, but Buxton and Kepler are the guys. It's expected to be one of them.

Buxton, who turned 22 in December, has been at or near the top of global top-prospect lists since being the second-overall pick in the 2012 draft. He can do pretty much everything on a baseball field: hit, run, throw, defend, you name it. Buxton is an impressive young player who looks like he was put on this Earth to play the game.

The German-born Kepler does not offer the same exciting tools package as Buxton, but he does have a very good two-way game. He turned 23 earlier this week. ZiPS doesn't like Kepler quite as much as Buxton even though he had the better 2015 and has a less ugly injury history, but the point is the Twins have both, and one will be the center fielder.

The Royals have earned the right to be considered favorites in the AL Central, though the division sure looks wide open behind them. Minnesota stayed in the hunt much longer than most expected last summer, and now they'll have a full year of Miguel Sano, Trevor May, and Tyler Duffey. They're moving in the right direction.

The Twins will have a kid in center regardless of whether it's Buxton or Kepler, and that's a big responsibility. It's an important up the middle position, especially since that person figures to have to cover much of the right-center field gap with Sano now roaming right field. I'm a believer in giving elite talent a chance, and Buxton certainly has elite talent. Kepler's not a bad fallback option.

LHP Steven Matz, New York Mets

ZiPS Projection: 3.37 ERA and 2.4 WAR
Competition: Rafael Montero, Logan Verrett

Matz, 24, made six regular-season starts and three postseason starts for the Mets last year, though he retained his rookie eligibility because he didn't throw enough innings and didn't spend enough days on the active 25-man roster. (He missed a bunch of time with a lat strain.)

This coming season Matz will be the lone left-hander in New York's stellar rotation. He may be the fifth starter come Opening Day, but that doesn't mean much. Being part of the five-man rotation is a big deal. The Mets are counting on Matz to have an impact every five days, and he showed last season he is capable of doing so.

As if getting a rotation spot for the defending NL champs on Opening Day wasn't enough pressure, Zack Wheeler is coming back from Tommy John surgery at midseason, and one of the Mets' starters figures to lose his rotation spot at that time. It won't be Matt Harvey, Jacob deGrom, or Noah Syndergaard. That leaves Matz and Bartolo Colon.

These things have a way of taking care of themselves, but surely the Mets want it to be Matz that stays in the rotation, not Colon. Montero and Verrett are legitimate competition and excellent depth. With Jonathon Niese traded, Matz is the lone lefty in the rotation, which could be a factor in the team's decision-making when Wheeler returns.

SS Corey Seager, Los Angeles Dodgers

ZiPS Projection: .266/.311/.447 and 3.9 WAR
Competition: Charlie Culberson, Enrique Hernandez, Elian Herrera

Realistically, there is no competition here. Seager will be the Dodgers starting shortstop this coming season and deservedly so. He was very impressive during his late-season cameo in 2015, and he has been ranked as the No. 1 prospect in baseball by every major scouting publication this spring. Seager's a budding superstar.

The Dodgers have some boom-or-bust in their lineup -- Joc Pederson was great early and terrible late last year, Yasiel Puig is coming off a down year, and both Yasmani Grandal (shoulder) and Justin Turner (knee) are coming off offseason surgery -- so they're counting on Seager to have an impact in 2016. This isn't a "let the rookie bat eighth while he gets acclimated" situation.

Seager, the 21-year-old brother of Mariners third baseman Kyle Seager, seems likely to hit high in the Los Angeles order -- he hit second or third in three of his four postseason starts -- while also beefing up the club's infield defense. Shortstop is a super-important position, and we've seen a lot of great young players at the position the last few years. Seager is the latest.

1B A.J. Reed, Houston Astros

ZiPS Projection: .261/.338/.456 and 2.6 WAR
Competition: Matt Duffy, Jonathan Singleton

There was no more devastating hitter in the minors in 2015. Reed, 22, hit .340/.432/.612 with 30 doubles, 34 home runs, and 127 RBI in 135 games between high Class A and Double-A last year, and now he's in position to skip over Triple-A to help at first base and DH.

Unlike some of the other players in the post, Reed has legitimate competition, however. The Astros gave Singleton a $10 million contract two years ago and will surely give him every opportunity to win the first-base job with Chris Carter now in Milwaukee. They want to get some return on that investment.

Houston also has Evan Gattis entrenched at DH. He recently had hernia surgery and is expected to miss 4-6 weeks, a timetable that suggest he should be ready come Opening Day. There's also the service-time issue. The Astros could opt to keep Reed in the minors long enough to delay his free agency (12 days or so) or his arbitration eligibility (roughly two months).

That said, the 'Stros are in the business of winning now. The rebuild is over and the time has come to put the best team on the field. Reed has yet to play at Triple-A, but he sure seems to be the club's best option at first base. Given his lefty might, Reed could have Kyle Schwarber-esque impact in 2016.

SS Trea Turner, Washington Nationals

ZiPS Projection: .258/.306/.378 and 2.2 WAR
Competition: Stephen Drew, Danny Espinosa, Brendan Ryan

Turner faces the most daunting path to MLB playing time among the rookies in this post. He's stuck competing against three veteran players, though it's worth noting neither Drew nor Ryan have been very good the last two years, and Espinosa has shown he's at his best in moderation, not when playing every single day.

The 22-year-old Turner has the loudest tools of the team's shortstop options -- his speed is a truly elite skill -- and also the best projection; his 2.2 WAR tops Drew's, Espinosa's, and Ryan's combined (1.8). Washington gave Turner a taste of the show last year, and that's something you do when you're considering giving a rookie an everyday job the following year.

The Ian Desmond era is presumably over and Turner, who put up a .322/.370/.458 batting line with eight homers and 29 steals in Double-A and Triple-A in 2015, is ready to take over. This is a logical move. Drew, Espinosa, and Ryan are nice depth in case things don't work out, but if Washington goes with any of those guys on an everyday basis over Turner in 2016, it will be a mistake.

Other promising youngsters like Carlos Rodon (White Sox), Luis Severino (Yankees), Eduardo Rodriguez (Red Sox), Ketel Marte (Mariners), Michael Conforto (Mets), Daniel Norris (Tigers), and Joe Ross (Nationals) all debuted in the middle of last season and lost their rookie eligibility. So while they're all about to embark on their first full MLB season, none are actually rookies. Let's call them important sophomore players on contending teams.