Shelton doesn't offer much in terms of pass rush either. He lucked out by racking up some sacks against crappy teams early in the season, which padded his stat line (then had 3 sacks over final 12 games or 5 sacks in 24 games if you take out his two big games). I'm not trying to argue he's a bad player, or would be a bad pick at 27, but you can't look at Goldman and say "he's not a 3 down player" and then look at Shelton and say you like him because he offers passrush. He's just not that guy. Brown, on the other hand, gives you nice passrush ability, but may not be that anchor you want at 1-tech on 1st and 2nd downs.
Just going by what I recall seeing, Goldman gets doubled all the time, but Shelton not nearly as much. Many of Shelton's plays are based off shedding a block and moving laterally, which he's exceptional at. But getting around a guy, even one-on-one, is not something he excels at.
