Background Info:

Okay, so, I'm a baseball pitcher.
So, right or wrong, I've been working hard to oxygenate my muscles and have been doing an insane amount of reps. (Usually 30)

Now that I'm taking a step back and looking to put on size, I've moved my rep range to 8-12 depending on exercise and body part.

That's all cool, but I don't feel that sore like I used to when I lifted with that insane amount of reps.

The Question(s):

Is this normal? (Since this is new to me and I'm just breaking in a new program)
or
Is this because my muscles are oxygenated?

Thank you for all replies/advice!