If it helps any, with Qubica,
my normal strike ball is around 13 - 13.5 at the backend.
My normal spare is around 14.5 - 15.0.
If I need to be precise, my spare ball speed will go down; If I'm throwing harder to convert wide open spares like the 7-10, it will go up.
2.5 mph difference seems unusually high.