Corey Hart, with the Brewers.
Target: Corey Hart, 1B/OF
2012 stats (didn't play in 2013): In 149 games, Hart hit .270, .334 on-base percentage, .507 slugging percentage, 35 doubles, 30 home runs, 83 RBIs
Hart is a tricky one. He's a proven power bat, and at 31, he's still in the prime of his career. But, he didn't play at all in 2013 after undergoing microfracture surgery in his knee and then needing surgery on his other knee before he got to see the field last season.
Not to compare Hart to the elderly Lance Berkman, but you can't help but raise a red flag after what the Rangers went through with Berkman in 2013. Hart is a risk because of his extensive knee surgery history, there's no way around that. He spent most of his career as an outfielder, but played some first base in 2012, so that could be an option for Hart, even though the Rangers would hope to see him in left field if they signed him.
If his knees aren't cooperative enough, then he'd end up being nothing more than a first baseman/designated hitter, but if his knees aren't healthy enough, the Rangers should steer clear. The plus-side here is that Hart would come cheap as he'd be trying to regain his value on the market, but it is a risk, and a risk very similar to one that backfired on the Rangers just last season.
He did have a really solid 2012 season and hit 31 bombs with 102 RBIs in 2010, with 26 homers sandwiched in between in 2011.