And what happens when Maatta plays more than a handful of games and starts getting exposed when all the forechecking attention is focused on him instead of Letang?
Rookie defenseman look great all the time, and then have a severe drop in overall play their sophomore year. Look at Letang for a prime example. Now, we can all sit and gush over Maatta and how he is the next Lidstrom, but the simple fact is that there are teams in the NHL, Maatta hasn't even played against. It is hard to plan against a player especially one with the skating ability and overall poise of Maatta when you have no game tape on him. The same thing happens with goalies, they look great one year and then everyone starts noticing their flaws and exploits them. See, Raycroft or Leclaire as a perfect example.
Letang is a necessity we need because it helps us gradually place players like Maatta and Despres in situations to succeed and succeed long term. I won't be surprised if Letang is traded in three or four years, when our slow approach to easing players like Despres and Maatta in ice time pays off and they are absolute studs.