If Noteboom is simply better at OG at this point than our other guys, so what? That doesn't mean that our other guys are dog meat; it may just as well mean that Noteboom is playing really well. Don't forget he's got a year or more on the younger guys, and he spent a lot of time in the weight room during his rehab.
I suspect there are other factors as well. By all accounts the Rams HOPE he is the LOT of the future (like next year). So nothing could be better than to play as a starter this year on the left side next to Whit. This should help him and give the Rams the film they need to decide whether Boom is their next LOT or they have to acquire one. Or, who knows, he just may turn out to be the next Saffold and he's too darn good at OG to move him next year.
But this is WAY too early to be thinking he remains where he is, or is a starter. Lots of time before Dallas.