"Much like Lackey, Tinney has been extremely selective. His swing rate is even lower than Lackey’s, at 30.9%. You could argue that’s too low, especially considering that he’s swinging at fewer than half of the pitches he’s seeing in the strike zone. It seems like both catchers could help themselves by being a little more aggressive on pitches in the zone. That’s obviously easier said than done when opposing pitchers aren’t giving them many pitches to hit, but as they continue to develop and get more professional at-bats under their belts, I’d expect that to change."
Tinney's low swing rate in A ball isn't as important as his contact rate, which unfortunately is also low. As players move up in the minors, the ability to wait out bad pitches matters much less than their ability to make contact. Tinney isn't at a find-another-career contact rate in the mid-fifties like Quentin Young, but a sub-70% contact rate of 67.4% in A ball is ominous.
For comparison with two rookies who have struggled with strikeouts, Colson Montgomery was at 76.8% in his first taste of A ball and Carson Williams was at 66.3%, almost the same as Tinney, but despite having exemplary defense and playing behind someone who brings very little offense, he hasn't been able to stick in the majors.
The Twins have had a weakness for years of thinking they could draft poor fielding power hitters with holes in their swings and convert them into major league hitters. It can happen, as evidenced by Kyle Schwarber (63.6%) and Hunter Goodman (68.9%), but it's rare. Most other power hitters with lots of strikeouts, such as James Wood (78.5%), Spencer Torkelson (74.4% in A+), and Nick Kurtz (83.1%), had much higher contact rates in the lower minors.
A couple more for the fun of it: George Lombard, Jr. - 75.4%, Matt Wallner - 66.4%, and Keoni Cavaco - 64.0% (career high).