To find the max speed of the football can be every easy. We know that the maximum speed occurs just before I catch the football, because gravity continues to accelerate it until an unbalance forces stops it, because of that it will be going the fastest right before that point. This means in order to find the maximum speed, we must take the horizontal velocity, which is constant thought out, and the final vertical velocity, which we found and apply Pythagorean Theorem to find the final velocity of the football, which will be the maximum speed.