Well, to be honest, I'd have to go back a couple of years to see who was available, whether in the draft, through FA, or by trade. I don't know. It's not my job to know. All I can say is that there is a real possibility that Marrone feels like he was given the shaft -- rightly or wrongly -- by having to start the season with EJ/Thad/Tuel.
I don't know if Marrone was totally on board with drafting EJ, maybe he liked him but not in round 1. Maybe there was pressure from Nix/Whaley to grab someone that year in the first round, regardless. Maybe Marrone was okay with drafting EJ, but wanted someone a bit more reliable than Kolb to start things out so EJ could sit and learn. Maybe there was a different vet he liked better, but Nix/Whaley didn't agree, or didn't do what it took to get him. I have no idea.
What I do know is that the combination of EJ-Kolb/Thad-Tuel was not a recipe for success, and I still think it's possible that Marrone was not totally on board with going into the season that way.