We were facing a 40 mph pitcher the game before.Yes, you can throw faster balls in the batting cage to help prepare for this one pitcher, but I'd not spend a whole lot of time worrying about an outlier. Train for what you're most likely to face. Within speeds of 60mph, I see more problems with batters not being able to adjust to slower pitching than vice-versa.
Was this really fast pitcher actually throwing consistent strikes, or were your batters chasing?