Tena is learning 3rd mostly on the fly with little time there.
his primary position in the minors the past 3 years has been SS. He had close to 2000 innings at SS in the minors with Cleveland from 2022-24, 147 innings at 3rd, and about 550 at 2nd (about 400 in 2022). So yes, Charley, Tena is more or less being asked to pick up a position he hasn't played much in the minors.
I think it's revealing that, in the 9th, he made a mistake pealing back to 3rd on a bunt rather than fielding it and getting the out at 1st. his other mistake earlier in the game was charging to pick up a ball with a runner approaching him going to 3rd. You don't get that sort of play at SS. he did start an around the horn DP, but he was able to sit back, field it on a bounce, and just make a good throw to 2nd.