He presumably picked the penalty takers based on who is best at taking a penalty in training. Let's be honest, Rashford is clearly a good penalty-taker. The fact that he was able to delay his run up and send the keeper the wrong way shows that he's got the technique, he just slightly fluffed the shot and it went an inch too wide (he sent the keeper the wrong way but then still insisted on putting it in the very corner when anywhere on that side would have done). Sterling is many things, but a good striker of the ball from 12 yards isn't one of them.
