If your point is that Tech would have won more games if it converted more 3rd downs throughout the season, I agree with that. Heck, if we converted all of the 3rd downs, we would have been National Champions! However, the statistics say we were 4th in the country at converting 3rd downs last season, including 3rd and longs. I would like to see statistics on our conversion rate for 3rd and longs only, as compared to other teams, but don't know where to find that. But the point remains, even if we are absolutely horrible at 3rd and long (which I don't believe is true), the fact that we still finished 4th in the country means that we rarely got ourselves into those situations.
It would be nice to be great at all things and be the best at converting 3rd and short and 3rd and long. We can always get better, but spending significant practice time for passing on 3rd and long means we spend less time on 3rd and short. In the end, if we finish 4th in the country in 3rd down conversion, I would say we have a pretty good strategy going.
As stated in my earlier post, I agree with you that our defense under CPJ has generally been very bad at stopping 3rd downs, including 3rd and longs, and that is a big deal. It has led to a lot of losses over the last few years, including the very same UGA game you referenced. If we stop them on 4th down, it probably never comes down to Tech having to convert on 3rd down late in the game.