Infield
Around the diamond
Eric Haase, Spencer Torkelson, Jonathan Schoop, Javier Baez, Ryan Kreidler
Bench
Kody Clemens, Jake Rogers, Andy Ibanez
Depth
Wenceel Perez, Andre Lipcius, Zack Short, Dillon Dingler
State of the infield
Plainly, they need a third baseman. The Tigers have toyed with the idea of moving Schoop to third and instead signing a second baseman with the notion Schoop would be better off with the upcoming rules regarding the shift, but moving Schoop to third base doesn't fix their predicament with their offense--and Schoop is likely part of a contingency plan at first base in the event Spencer Torkelson is not ready.
It's a challenge addressing the need in free agency--third base options were slim to begin with and have only gotten slimmer, so if their intent is to address the position adequately, they'll likely need to do it via trade. I don't love the idea of gifting Ryan Kreidler or Andre Lipcius the job out of spring, but would happily oblige if either or both played their way into a regular role somewhere around the diamond.
Unlike the crowd, I'm actually okay if the Tigers leave the catcher spot as it is, although some of that will hinge on how much they are expecting Eric Haase to patrol the outfield. Rogers was showing signs of life offensively prior to his injury and Haase likewise had a strong finish to the season after a sluggish start with the bat--and really, the standards for offensive production out of the catching position might be the lowest they have ever been league-wide, so even perceived shortcomings may not be bad relatively speaking.
Even so, there is an argument to be made for the club to still address catcher, third base, and second base before season's start--making this position group by far the weakest of the club.