I've heard that the splitter is a pitch that is more commonly found in pitchers who come to the U.S. from Japan. Tanaka (NYY) is just one example. I've heard that American born pitchers don't throw it as much as compared to decades prior because it can cause arm issues, and that Japanese born pitchers often bring the splitter with them when they enter MLB organizations because they are already taking a big leap by moving to North America anyway. It's a fascinating pitch, and I've noticed some difficulty hitting RHP splitters with RHB on The Show. I mainly find splitters in the RHB's low & inside quadrant of the zone specifically difficult against the CPU (HOF setting) and I often swing and miss at those strikes. It's could be an interesting pitch to add to a RTTS character's repertoire.
In Japan, I think it's called the "shuuto" and is a unique version of a splitter with more depth.
I messed around with throwing a splitter when I pitched, but man that started to kill my forearm after a while. Some pitches just didn’t feel worth throwing no matter how nasty they were.