Did anybody summon me?
Just wanted to add one point about this comparison: Championship clubs don't compete in Europe, Leverkusen does, which makes their schedule harder than Middlesbrough's.
Besides that I do actually agree that Carrick's league experience might be more valuable to United right now than Alonso's, simply due to the fact that Carrick is just in the middle of the league with a squad that's not near the top of it (similar to United in the PL right now) and more or less has to go against the ownership, while Alonso probably has been given the most balanced and one of the strongest squads in the BL. He did prove that he can work through tough situations last year however, but what he now is doing gives him the experience to takeover a dominant side like City, but less so a struggling club like United.