Well, here are a few of his moves, or mis-moves.
In 2003, when Andy Pettite went free agent, Cashman did not really try to keep Pettitte from going to Houston. Now, Pettite came back, but this was after injuring his arm a few times, and he was not the same Pettite who won the world serieses for the Yankees.
To correct Pettite, the Yankees brought in Carl Pavano and Randy Johnson. Johnson has no affinity for New York, and while he won a few games, never won a big one and then got hurt. Pavano will end up a total bust pitching not even half a season's worth of games.
Cashman is currently trying a strategy of easing in some of their best minor league pitching- Philip Hughes, Tyler Clippard, Matt DeSalvo, etc. However, so far all of these guys have been so green, they are not the answer.
What Cashman should have done was paid what it took to brinig in Matusaka. Maybe Dice-K is not the be all and end all, but he's probably better than Petitte, Clemens, and any of the Yankee youngsters ruining the back of their rotation right now.