Why aren't you sure the Jordan Roberts signing was down to him, but the rest are? You can't take a positive signing away from him, based on (as far as i'm aware) no evidence at all, just because it suits your argument.
on the other signings, none of them have really kicked on, however Foley, Smith and Nolan are all injury related, which is completely out with anyone's control. That's not to say they would or wouldn't have been successes though, I actually thought the Foley and Nolan signings would have been good business albeit not very flashy, at the time the only two players over 30 in the squad were Carson and Chapman and the squad, never mind the team was crying out for some experience.
We also need to remember how difficult the window is to sign real quality, never mind in the middle of a pandemic, convincing guys to sign for 6 months and move to another country where they can't leave the house can't have been easy.
His signings this summer will be when he is judged.