I don't know much about Holmes, but everything I read about him suggests he is not ready to play this year. My assumption is that Baker & Svitek compete for LT, and the loser gets axed, with Holmes being developed as the swing tackle.
TD definitely falls in love with a couple of guys too much, and takes them early. Holmes seems like a long project player...a 5th rounder type. Hopefully he can be coached up quick.
Regardless, the Owens, Dent, Holmes pattern of 3rd rounders who were expected to go in the 5th, instead of getting 2nd round talent is hurting the team. 3rd rounders are still valuable. Take a gamble in the 5th, 6th, 7th...because those guys aren't likely to make the squad, so a boom/bust guy is great.