Hmmm... not sure I agree with much of either of your conclusions. We've had PLENTY of teams that have had fourth guards. I don't disagree that these guys don't often log significant minutes, that our backcourt rotation tends to go deeper than 3, that is hasn't been a frustrating problem dating back to 2013 -- those are the points of your post I agree with -- but I'm thinking big picture here. Having three guards isn't good for practice, because you can't field two legitimate units to scrimmage. Let alone as emergency depth if one gets injured, or has an academic issue, etc. No doubt, we're going to ride it out with three and cross our fingers that nobody gets injured, but I'd sure feel a lot better about the roster balance if we had a fourth scholarship guard.
I also don't know that I agree that Lydon is a "true' small forward, let alone one of the better ones we've had. My opinion only, but it is going to be one of the developments that could determine next years team's potential--will Lydon be able to log big minutes as the nominal 3, or will him playing alongside Roberson / Coleman not work? Moyer could be a 3, too, but I see him as more of a stretch 4 and think that's where he'll eventually end up playing the majority of his minutes. Lydon shoots the ball well. That's about the extent of his SF skill set, at least based upon what he showed last year. Can he handle? Is he a passer? We'll see. But I think it is a reach to suggest that he can do some of those versatile things that 3's are called upon to do in our system better than the players you reference above. Granted, some of them did certain things better than others [for example, Nichols was a better shooter than some, but was subpar putting the ball on the floor].