Ryan Switzer was not a good pick. That isn't a negative take. It is just an obvious one. Not all 4th picks are going to turn into a pro-bowler or top player, but you at least hope for a solid, consistent contributor. Swizter did nothing as a WR. He had a few moments as a return man, but wasn't consistent. I don't think 321 yards receiving over his entire career clasifies as good for a 4th rounder. That is a very low standard. A good for a 4th rounder probably averages close to 300 yards per season.
Going a bit further back, Marion Barber III was a 4th round pick that turned out pretty well for Dallas.