Can someone explain the difference between "Pitch Type" and "Pitch f/x Pitch Type" on fangraphs? I assume it's just 2 different ways of recording the pitch type? I was just looking in on Jerry Blevins again (as I as going to point how a sign Jose & Blevins + trade for Dyson would be a nice way to finish the offseason) and I see under "Pitch Type" it says he only throws a fastball, curveball and change - but under "Pitch f/x Pitch Type" it suggests he throws a slider 10% of the time.
I see the slider velocity is only a couple MPH lower than his fastball - is it just getting grouped in with his fastball on "Pitch Type"?