Carroll will be ineligible for next weekend's trip to parent club Liverpool.
"That's a couple of really good games Andy has got under his belt now and the goals should give him confidence. When you're on the move inside the box it gives you a chance to score goals and he has taken them very well. Another good all round performance and that's what we've been looking for and that's exactly what we want from the last eight games," McDonald told whufc.com.
"It's a shame that Andy can't play at Liverpool, but they are the rules. It will give someone else a chance and they will be coming into a team that's full of confidence after a good win against a top-half Premier League team."