Before Wenger came to Arsenal he'd only won 1 league in France and a cup and a few cups in Japan and he's seems to have done OK here. Silva has won a few leagues and a few cups he was just unlucky to get Hull and Watford I cannot see Wenger would have done much with them either.
Tin hat on.
Wenger aside (so i don't think football will ever see a Ferguson / Wenger manager again), for Watford last season my memory was they were playing attractive attacking football and had an organised defence. it was like they'd transformed preseason from how i remember them the previous season.
Upto Dec 2 i.e. before all the nonsense start in public at least, Silva's record was P 15 W6 D4 L5. The P15 included Win against Arsenal, Draws with RS and Spurs and losses to City, United, Chelsea and us. So i reckon that's a Europa League place trophy performance record. i'm guessing for all he talks about Champions league that Moshiri would be happy with Europa league consistently for next few seasons.
He almost pulled off a miracle with Hull in almost impossible circumstances.
So while he isn't a marquee manager, i'm behind him to get us back into Europe at least (not saying much like because we finished 8th with horrible performances and miserable tactics all last season).