Mandzukic is one of the top CFs in the game, why do you limit his role to a backup? he will play 30+ games this season, close to 40 if he stays healthy. Zaza over 20 games. they both are here for a reason, because without them we would have Morata, Dybala, Coman and we would still buy 2 strikers, maybe even more expensive than those 2. thats especially in a year we are losing both Tevez and Llorente, who wasnt that important for us last season, but still played a significant amount of games. Morata has a high chance of leaving next summer too, so both Zaza and Mandzukic make perfect sense.
and we arent "wasting money"? we are merely spending our transfer budget on 2 players the board and the coach decided that are needed. if we havent bough those 2, we would buy other "backups", we wouldnt "save the money" and we also wouldnt have more money to spend next year because of it either