Man, I just don't see that at all. First of all, I thought he was pretty clearly better than Salaam last year. So, if Salaam is a journeyman, then he's already better than a journeyman. We did very little last season in sliding protection towards him which indicates confidence in him. And, I thought he won a lot more battles than he lost. IMO, he had bad games against Harrison, JAllen, Porter, Freeney (at Indy)... other than that, he was good. For a rookie with as little experience as he had at tackle in college, how could he not struggle against those guys. After all, probowl tackles struggled against them. Also, I thought he looked extremely athletic and was excellent run blocking on the second level and on the backside.
ALso, I'd rather have him right now protecting Schaub than guys like: Flozell Adams, John Runyan, Orlando Pace, Jake Long, Willie Anderson, Max Starx, and many others. Those are all guys considered to be plus LTs who clearly lack the athleticism to block elite rushers one on one. Granted Brown struggled to do it but only because of a lack of experience not because he lacked the strength or quickness. Since he's also said to be very coachable and a hard worker with no injury history, I think he has the potential to be great! Another thing to note is that he committed very few penalties last season. So, while the sack number was high, is overall number of negatives was not very high- basically, he hasn't learned to hold yet.
Salaam fell off this season, and isn't very good anymore. Most of the other guys you listed have a combined age of over 9000, and are either over the hill, or rolling down it. Jake Long was solid this year. All of the tackles taken in the first round except C.Williams, and D.Brown performed very well in their rookie campaigns.
I give Brown props for his run blocking at the second level. He is much better than advertised. He did look decent at times in pass protection, but you're supposed to win 99% of your battles at LT. I actually thought Brown looked best at the beggining of the season with mostly solid play, and just a few bad plays that stood out. Later in the season his sack numbers might have gone down, but he was getting beaten more. Schaub just understood that he didn't have reliable blind side protection and got the ball out quicker. If he had to play full time instead of getting spelled, i think he would have given up close to 20 sacks, and alot more holds from tiring out.
I also wasn't all that impressed with Brown's athleticism to be honest. He looks good running in a straight line, but for a smallish guy, who was drafted almost completely on athletic potential he really doesn't seem all that quick, and agile. He also looks kind of soft, and needs to lay off the twinkies.
I still think he can be a good-very good player if he works hard. Like I said, I see his max potential being Matt Lepsis level. I hope that he developes to be a good player, and proves me wrong. It just doesn't seem likely. I'd still prefer they move him inside, and draft a LT with actual Elite potential, or sign Jordan Gross away from Carolina.
I think some people get caught up in where he was drafted, and either root for him to suceed, or fail base on that. IMO where he was drafted stops mattering the second the guy signs on the dotted line. He's just a guy on the roster, with a contract he needs to live up to. If Brown were a 6th round pick, I doubt most people would be so supportive, but since we spent a 1st round pick on him people feel more invested in his success. For examples of this unbalanced support/complaining about players see Babin, and Faggins. People didn't like that we traded so much to get Babin, and turned on him as soon as he didn't explode onto the scene(Even though, IMO, he had a pretty decent rookie campaign, and was hurt the first half of his second year). On the flip side, since Faggins wasn't a high round pick, people judge him based on his performance on the field. They don't have the big emotional investment in his success that they do with D-Rob, or D.Brown.