Didn't he play on the D-League team about 80% of the year in his 1st season. So technically last season was his rookie campaign. Both players improved a little bit defensively after their 1st season. If DMo was massively better like you are suggesting here, he would have played more meaningful minutes, especially in the playoff's.
Well, that's because it's the weakest spot in the starting 5. He's not bad, but you got an all-star at the center and SG positions. Had a solid SF in Parsons. And an NBA all-defensive second team player in Beverley at PG. Jones just wasn't there yet. He is a decent player and still has good potential, but Bosh would be a game-changer... and he would replace the weakest spot in the starting 5, so he would have been extra helpful. Hell, Morey replaced Asik with Dwight even though Asik was awesome. Morey looks to upgrade wherever he can.
The plan was never to start Jones as many games last season as he did. Wasn't the initial plan to start both Asik and Howard? Although that didn't initially work, Asik's injury provided Jones with an opportunity which he took with both hands. Would have loved to have upgraded with Bosch and even had we done so, I would like to keep Jones still. Still think he did a really great job last season and hoping he continue his development and get even better.
I don't argue with the logic here, but I think the point is, we have a championship quality team right now. We need a 4 who has "it" now. No knock on Terrance Jones, it's just that we have two stars in their primes and we can't wait a few years for Terrance to become a more reliable option.