Yes, but emphasis on takes time. Pancada has been stuck on sentinel for a solid 3 months now and he went from going +10 in all his games on LOUD to always going negative.
If you're a team that desperately needs someone to fill a role, are you really going to want to wait 4+ months for them to actually get good at that role or just sign a sentinel player in the first place? why waste all that time for results that aren't even guaranteed? you're not even guaranteed a good performance from a sentinel player in the first place so why pile risk on top of risk?
If you're going to sign Valyn, don't make him play another role for god's sake.