A couple things to unpack here.
1-Your point was that Hernandez has issues but we have Kugler to remedy them. Of those two points, neither really has evidence to support your statement. Hernandez has had these issues for multiple years and has not been able to remedy them. It is a fair question to ask what will be different. Kugler has not developed any young player on our roster. Humphries is pretty much the same player he was in 2019 and Josh Jones is bad to below average in his reps. Cole didn't develop and neither have any of the other young OL guys we have. So, Kugler coaching him up doesn't really have any backing either.
2-Do I like the signing? Yes. Hernandez is a much better option on our depth chart than a guy like Garcia but not as the penciled in starter. You bring in a player like Hernandez to see if he can play his way into a larger role but you should not be counting on it. I view Hernandez similarly to Sean Harlow. Bring him in, see what he has, and if you strike gold, great. However, that doesn't make him any sort of answer when it comes to our offensive line.
3-So, why am I commenting? Because people on this thread are stating they are uncomfortable with the idea that RG will be a battle between Murray/Jones/Hernandez and you are stating they are wrong for being uncomfortable. That is incorrect and I feel it appropriate to point that out. None of those players have shown they are good options at RG.