Digne didn’t need 3 or 4 months to settle, its been one game so far for our new left back and he did ok. We have Godfrey as cover if that’s the case. The ideal centre back partnership at the moment is Mina and Keane if fully fit anyway
Digne was 25, had played for Barcelona, Roma, PSG and a title-challenging (or winning, can't remember exactly which) Lille side. He was already an experienced France international who'd only missed the 2018 WC squad due to not playing at Barca in the back half of 17-18.
I think
Mykolenko is going to be a good player. He's very raw though. He's come straight from the Ukrainian league which is in no way comparable to the experience Digne had. At least he's played at a big international tournament and this year in the Champions League, however. That will set him in good stead. He hasn't played wing-back really and throwing him into that system is possibly going to be detrimental but we'll see how it goes.
But you can't really compare the two players in terms of relative experience when they came in.
Mykolenko is going to need time and patience. He got skinned a few times the other day and gave away silly fouls just like Digne gets slated for. It'll come with time though, was always going to be a tough debut and he's got 120 minutes under his belt and looked more assured as the game went on.