West Ham United management were happy with the new additions for their 2-2 draw against Stevenage Borough.
Aaron Cresswell and Diego Poyet both started the game, while Cheikhou Kouyate appeared at half-time, and McDonald believes there is plenty more to come from all three.
McDonald told West Ham TV: "The new boys fitted in well. In the first half, Cresswell did well and put a couple of good passes forward and defended his far post really well, so that's excellent. Cheikhou had plenty of the ball in midfield in the second half and moved it on really well, so that was good and young Diego had plenty of the ball as well and stuck his foot in.
"The three of them have settled in well and integrated into the squad while we've been away in Evian in France, and we've still got plenty of training sessions to sharpen them and everybody up."
