I’ve watched Mariano Rivera pitch countless times, and I’ve seen him throw that cutter 97, 98 miles an hour when he has to. Most of the time he throws 93-96, but when he turns it on, look out!!! And he does it so effortlessly… :o
I saw him pitch against the Jays on TV twice this year. The first time he dismantled the heart of the order (probably Rios, Wells and Overbay at the time) with the cutter. Had Vernon questioning his own existence. The next time, later in the year, same part of the order gets up, ready for the cutter and he threw maybe two or three over a full inning. Threw 95-96 mph four seamers all day and it was just as effective.