There is psychological research showing that the brain concentrates in brief bursts. A hitter would be best positioned to perform well if within one of these focused intervals. Many pitchers seem to realize this phenomenon at least subconsciously. They seem to keep the hitter waiting as long as possible without causing him to step out. The pitch clock can disrupt this pitcher's game. One of the pitcher's advantage is that he is the one who knows exactly when he will throw the ball.
The pitch clock may also disrupt the pre-pitch routine of any hitter or pitcher with an elaborate pre-pitch ritual. The longer somebody has been doing their routine, the harder it may be to change.
Where older hard-throwers, like Wheeler, may suffer is losing the necessary time to catch their breath and restore their strength between pitches, especially in long innings.
In most matchups, I expect the pitching clock to benefit the hitters. I expect the limitation on throws to 1B to also benefit the hitters, as well as, obviously, the baserunners.
