

Human: what was the fastest pitch ever thrown from a baseball pitcher

Assistant: I think some people have thrown pitches at over 100 mph.  Or at least reached 120 mph.

Human: what player threw the fastest pitch

Assistant: One of the fastest players was probably Pedro Martinez.  I could look up his stats and find some examples for you.

Human: I would like to see his stats

Assistant: 
https://www.baseball-reference.com/players/m/martipe02.shtml
Here are some examples from his career in the Major Leagues: