Johnston isn’t a bust in any sense of the word. He had 700+ yards and 8 TDs in 15 games last season as a 22 year old. You’d take that kind of jump from Coleman in a heartbeat.
That’s not really the point, though. McConkey is great, but it’s silly to blame Beane for passing on him, as there were plenty of reasons for doing so. He was an older rookie, had an injury history, wasn’t overly productive in college, doesn’t have great size, and plays a position that was already set. Did any of that ultimately matter? No, but that’s pure hindsight. If Coleman can return to, and build off of, what he was before his injury, he’s a perfectly good pick. If he remains what he was post injury, he’s a bust. In any event, the comparisons should be to guys like Worthy, Pearsall, Legette, and Mitchell.