Spitz is a good guard. He should be a starter this year. Colledge is a high end back-up, the way it looks now.
You trade both of them away and we're paper thin at OG. I asume that our starting line-up would be Clifton - Lang - Wells - Sitton - Tauscher. That'd leave us with Dietrich-Smith and Breno Giacomini as back ups.
So we'll weaken our starting line-up by trading away Spitz. We trade away Colledge who would be our nr. 2 on the depth chart on nearly every interior line position (Spitz would slide to C, Colledge at G if Wells goes down). We have to plug in Lang at G, which means that we still don't have a RT of the future on the roster.
And for what? A back-up QB and a 5th round pick. If we weaken this O-line, we'll need 5 back-up QBs. And you don't have a very high hit change in the 5th. Even in as deep as a draft as this one.