3 man requires a sweeper. But our only backup sweeper is Marrone who will end up playing with Caceres.
I don't like that combination, quite frankly. I think they will obviously lack chemistry but also marking and aerial ability is suspect with both of them.
I also like a 4 man defence better without Bonucci. I think Caceres is better as a CB because if we want to play aggressive, our fullbacks will be up the field and I think Caceres has more range and 1 on 1 ability needed in case of counters.
I would still be scared that our possession would drop without a 5 man midfield and we'd have to actually defend instead of just winning the ball back with ease like we do in the 3-5-2.
I think we'd be weaker in possession and we'd give up more shots but they'd potentially be less devastating then with a Barza-Marrone-Caceres backline.