Manager sees the players train everyday, talks to them and has first hand experiance of how the players interact with each other. I would think hes in the best position to decide who the captain is. Rather than us seeing them 90 mins every week or two.
The team needs time to settle in with new team mates , fitness training ,tactics and the like . No way after 4 games can they be expected to play and gel like a settled team . Whatever people say it will take a bit of time .