Aguero has one assist (I think) this season and Kelechi's link up play is average at best. Play both of them at the expense of one of David or Kev - two of the most consistently creative players in the league - and I guarantee the number of chances we create will drop dramatically. Jesus is a different story but he's been available for only a tiny number of games so it's hard to say.
As well as this, an extra man up front means one less man on defence/ attack, decreasing the probability of us retaining possession to create our chances.
If I remember correctly, Kevin has hit the post as many times as anyone in Europe's top leagues this season and that kind of encapsulates how we've let things slip in terms of the fine margins not going our way.
Personally, I don't think there's anything wrong with our buildup play or number of strikers. We've just simply not been clinical enough with what we've created.