I think Wallace's no-nonsense, straight-talking approach, admired by many including me, probably counted against him for the NATO job. Whatever his qualities may be (and I'd agree his record is a bit of a curate's egg, although he certainly has some good points), he's not exactly a diplomat - whereas any top multi-national organisation requires as leader someone who can carry off the sort of mannered, courtly gavotte that somehow combines being persuasive with carrying everyone along without too many ruffled feathers. A talent for calling a spade a spade doesn't always go down well in multinational circles, refreshing as it may be to many of us. I've also seen suggestions that the US may have regarded Wallace as a bit too pushy in relation to the Ukraine agenda. The US is used to calling the shots and setting the pace, and Wallace's high-intensity approach may have hustled them a long a bit more than they appreciated.