Silva was never known for blistering pace and that's not what we miss. Silva was able to take the ball in highly congested areas and would be able to work in those very tight spaces that other players just simply can't manage. His ability to receive the ball and then redistribute it all whilst twisting and shielding the ball from 2/3 players was second to none. He used to absorb players to him which always created spaces for the forward players. I think, and ofcourse that's just my opinion, that's what's missing. Rodri isn't that player, Gundogan isn't, KDB isn't either. All great players, but they just don't offer that ability to be the puppet master in that congested central area. Could Foden or Bernardo take that mantle - quite possibly. But they seem to be getting used in a more direct role.
But as has been said, Merlin was a once in a generation sort of player. We can't expect to replicate that like for like and need to adjust to use what we have most effectively.