4th rounders rarely produce and that in itself is not fair to expect them to do much, but as pointed out in this thread, doing a little versus doing nothing is a difference, but this isn't one isolated event. On the offensive side, you can start a list of questionable results and each one can be explained with some specific logic as an alternate possibility, but the pattern is so strong, that the common element of offensive coaching being a significant problem is a higher probability than all of the edge cases being the root.
