The Twins on Tuesday traded backup catcher Chris Herrmann to Arizona for minor-league outfielder-first baseman Daniel Palka.
Palka, a left-handed hitter, has hit 60 homers in the lower levels of the minors, including 29 last year for Visalia in the High-A California League. Power is an important tool, and he has it, but at 24 he's a bit old to be in A ball. Presumably he'll be at Double-A Chattanooga in 2016 to fill the Adam Brett Walker role of a right fielder who either hits home runs or whiffs.
More significant than the addition of a low-level outfield prospect is probably the deletion of Herrmann, who has spent parts of the past four seasons with the Twins but never got much playing time -- 389 plate appearances all told -- and didn't hit in what time he did get (.181 batting average). Herrmann was the primary backup to Kurt Suzuki last year, and now he's gone. The other catcher who spent some time with the Twins, Eric Fryer, took free agency after being outrighted last month.
I still suspect that if Herrmann were given regular at-bats in a platoon role he would hit a bit, but the Twins never saw fit to give him that chance. The Diamondbacks ran six guys behind the plate last season, and maybe Herrmann will get a shot there.
Meanwhile, the Twins have no obvious backup to Suzuki, much less somebody capable of pushing him for playing time. Josmil Pinto is the only other catcher on the 40-man roster. He missed much of 2015 with concussions and isn't a good receiver anyway, so the Twins can't count on him. Presumably there will be a more reliable option on hand when training camp opens, either via free agency (A.J. Pierzynski, perhaps) or by trade.
Baseball Amercia's analysis of the trade is here.