OGS is doing a good job compared to other recent United managers. It's shit compared to old United standards under SAF, but good in comparison to them. But he has a better squad than Moyes, van Gaal etc, so how well is he really doing? The bare minimum is a good description. The same epic inconsistency as Juve, but Juve on our best day have not played as well as United at their best this season.
For Juve to do as well as previous coaches you have to win the scudetto. Pirlo probably isn't going to do that this season, but we shouldn't be totally surprised. At least OGS had an apprenticeship at Molde to try his ideas out. Pirlo didn't even have a proper pre-season, we started off with a 10-15 point handicap while he figured things out, and conditions haven't been right for us to go on a run to make ground up.
Chiellini is a very smart guy but it doesn't mean he will be a success. For individual success you need success across the board. When we started off with Marotta we hired Delneri and it was a failure, they took a gamble on Conte and it worked spectacularly. From then on every department seemed stronger because results followed. What happens on the pitch dictates how everyone at the club is seen.