This strengthens the Jets when it comes to matching up against the Patriots.
Cromartie is an upgrade over Lito Sheppard, and his style of play is a good match for the type of defense that head coach Rex Ryan plays. Ryan also has a strong track record of helping corners regain confidence, taking talented players who haven't performed to the level they are capable and getting more out of them.
Cromartie's presence should help better balance the Jets defense, allowing the unit to better match up against Patriots receiver Randy Moss and whoever is on the opposite side of him. Both corners (Cromartie and Darrelle Revis) have length that will make it harder to execute in the vertical passing game.
If there is a downside of the deal to the Jets, it is off-field concerns with Cromartie, as well as his weakness when it comes to tackling.