Not just defense, but poor fundamentals all around. The overall identity of Baldelli's teams.
Fix it all. Be better at playing the game than other teams, rather than worse..
And BTW this is completely separate from talent. The Twins need talent upgrades sure. But they also need, as an organization, a return to valuing and emphasizing playing the game correctly. That concept has been scoffed at for the entirety of Baldelli's tenure, right from day 1.