In a few short months, Detroit Tigers slugger Nicholas Castellanos will be one of the most sought after free agents on the market. He currently leads the league with 21 doubles, and has hit .282/.333/.489 with 128 doubles and 74 home runs since Opening Day 2016. Also, Castellanos is only 27; he turns 28 next month. Whichever team signs him will get his prime years.

Castellanos can really hit. The problem? He's not much of a defender at all. The Tigers have moved him from third base to right field, and, since the start of that 2016 season, his minus-29 defensive runs saved put him among the worst defensive players in baseball. The Tigers asked Castellanos to play first base last September, but he declined. From Cody Stavenhagen of The Athletic:

"I was like, 'No, man,'" Castellanos told The Athletic in May. "I'm gonna stick in right field, and I want to do good out there. If I move to first, it's gonna be when I'm older and can't play right field any more. Before that happens, I want to be (in the outfield)."

Castellanos has continued to play right field exclusively this season and again rates poorly defensively. On Friday, he told 97.1 The Ticket's Jeff Riger he would happily to move to first base -- or any other position, for that matter -- if the Tigers give him a long-term contract extension. That has not happened, so Castellanos remains in right field.

Here's what Castellanos told Riger, via Riger's Twitter feed:

"I told them, if you offer me an extension and show me that I am a piece of the future, I'll play first, I'll even throw bullpens for you but give me that security. I've been open to any extension talk but that hasn't happened. They said I turned down one in the offseason of '17 but that wasn't true. I've also had conversations with (GM Al Avila) with him saying it doesn't really make sense where we are to be handing out extensions. I don't have a college education but I can pick up the pieces here and put a puzzle together. I'm not saying this is 100% what it's going to be but if I'm a gambling man I don't see them offering me an extension at this point and time."

Castellanos added he has bounced around so much defensively in his career -- starting in the minors, he's moved from shortstop to third base to left field back to third base and now to right field -- that he's been unable to settle in and get comfortable at one position. That's one reason he wants to stay in right field rather than move to first base.

On one hand, interested teams could hold it against Castellanos that he didn't move to first base and be a team player. On the other hand, since when does being a team player pay? Adam Jones slid over to right field no questions asked when the Orioles called up Cedric Mullins last year, then still had to wait until March to get signed. Jones is hardly the only example.

The Tigers have 97 games remaining this season, and a 97-game crash course at first base won't help (or hurt) Castellanos' free agent stock. And, truth be told, nether will another 97 games worth of experience in right field. Whoever signs Castellanos will sign him for his bat. They'll figure out the defense later. After all, he says he'll play any position once he gets that long-term deal.

It's not often a player stands up and says he's doing what's best for him. Castellanos saying he'll do whatever the team wants once they pay him is refreshing. It's not like the Tigers are a postseason contender. Castellanos is looking out for himself and isn't afraid to say it. That won't endear him to some folks, but he's being honest, and everyone knows exactly where he stands.