Thanks for the analysis. To answer your question: I do definitely feel that hitting the volley against a player is very different from hitting against the ball machine. Even in warmup hitting balls down the middle, I have some trouble controlling the depth of the ball and getting solid contact. I suspect that it is harder against players that have more topspin. When playing sets, I usually do not miss long. On high balls, I can miss wide or just pop the ball up. On lower balls, I can miss into the net. I also have missed balls into the net on second volleys. I asked about footwork because on second volleys, when I miss, I fell like I am flat footed and reaching for the ball.
At this stage, I feel like I want to just get the basic volley solid; hit the easier volleys well and put away the ones I should put away.
To better simulate match play, I’ve been setting up the Slinger machine around the service line, so that I have less time to react. Usually, I start from just behind the baseline, to simulate the first volley position.
But, as you said, the Slinger always shoots the ball in the same direction–do you think it would be better for me to use an oscillator to vary the direction of the ball? Or should I vary my start position, for example, starting from just inside the baseline to simulate movement up from an approach shot?