After Derek Jeter's injury-filled 2013 season, the Yankees have a lot of questions at shortstop that need to be answered. They need to know how much Jeter can contribute, and where he can play. They also need to know if they can re-sign Brendan Ryan or nab Jhonny Peralta off the free agent market. If neither can be had, Clint Barmes could be an interesting Plan C. If it's come to this, things have probably gone terribly wrong, but that doesn't mean it will be a terrible signing.
Barmes isn't much of an offensive shortstop, but he does bring the defense. He has a .246/.294/.383 (71 wRC+) career line, but has hit 25 home runs over the last three years. As a right-handed hitter, he hits lefties at a league-average rate (98 wRC+), but he's utterly useless against righties (62 wRC+).
He just completed his fourth season in a row with 11-14 defensive runs saved in a season. He also put up his fifth season in a row with a UZR/150 in double digits. He also provides above-average defense at second base and has limited time at third base.
He's essentially a poor man's Brendan Ryan. They're equally offensively inept, but Ryan is a better defender. Even if the Yankees are only looking for a backup shortstop, they can't look to Eduardo Nunez anymore. While he has a slightly higher offensive track record (86 wRC+) than either Barmes or Ryan, he's never posted a positive UZR/150 or defensive runs saved at shortstop throughout his career. If you're going to get the same offense, you might as well go with the better defender.
Barmes will be 35 next season, so he won't have the "upside" that Nunez has, but it's better to know what you're going to be getting. The Pirates had previously signed him to a two-year, $10 million contract, so another one year deal at $5 million could be all he costs. The Yankees should still go for Ryan or Peralta first, but Barmes would be a good backup backup plan.