it could be a few things why the players arent getting a whole hand onto the ball.  

yes footwork.  a poor take off will dramatically slow down the drive to the ball.  

reading the play too late, so not concentrating enough on the game and whats going on.  

hands being too relaxed or soft, so the ball touches but can not be controlled.  

the strength of the pass.  the stronger the pass the more direct the line is so the harder it will be to change its direction into your hands.  

taking your eyes off the ball so your hand does not get into correct position of the line of the ball.  

not jumping or flat feet. (refer back to first comment ref footwork).

im sure one or more of these will help change the result of your players tips.