Flick has played quite a bit of 4-3-3 lately, or at least a similar version of it with Dani Olmo as a pseudo number 8 and Fermín López playing a little bit closer to the midfield instead of a second striker, but what we actually get in that setup is a very attacking 4-1-4-1 with Frenkie as the single pivot. It worked wonders against Elche recently, but it also asks way too much of Frenkie.