The Wolves don't fit very well together which is the bigger problem. Dieng and Towns aren't a great fit. Lavine and Wiggins are both poor defenders. It isn't a question of age as much as fit and team construction. Seattle/OKC won 20 games in Durant's rookie year, 23 games in Westbrook's rookie year, and 55 games in Harden's rookie year. In the playoffs they had 30 year old Collison in the rotation, but the next oldest player was 26 year old Perkins (who was obviously a vet at that point). Durant, Harden, Westbrook, and Ibaka were all 21 or 22. Thabo Sefolosha was 26 and started over Harden. Maynor and Cook were both 23 and the other guys that played in all 17 playoff games for the Thunder that year. They made the WCF that year and the next year were in the Finals with basically the same team (before they traded Harden that summer). That team just fit well together once they moved Green for Perkins. They had a defensive/rebounding center in Perkins, a defensive stretch 4 in Ibaka, an offensive juggernaut at SF and SG, and a monster PG. Russ and Durant were solid defenders, and they started Thabo over Harden because he was a superb defender.
Roster construction is important. The Wolves need a defensive oriented wing, a better fit next to Towns (even if just for 15 minutes a game - a guy like Bogut for example), and they need a 3 and D PG. Rubio is a terrible shooter and while he is a good steal generator isn't a great on ball defender. They need to find a better fit there.