It's because the knuckleball in this game is tethered to its end point, only varying as much as a fastball would. They basically took a fastball, slowed it down, and randomized its path. There is no break. 2K had a fantastic knuckleball. You never knew where it was going.
2K gets knocked a lot (and somewhat rightfully so, it was a buggy game), but they had stuff 10 years ago that The Show still doesn't have.