Making adjustments can change velocity. If he is throwing more strikes it's working and sometimes velo has to give way to command in the beginning. Most pitchers early in the season start out with lower velo, building strength and stamina as they go. Long toss everyday is what one is supposed to do for conditioning, but if throwing BP's every other day (makes for 3-4) and long toss, it may be too much? What does he do the day after a BP or after BP? Is he getting the lactid acid out? Is it long toss or just warm up toss? And is there pitching practice or just BP? Kind of confusing, I agree with Caoch, what he is actually doing. As long as there is no pain or discomfort, could be a tired arm.
Pitchers work load increases not decreases. My son tosses the day after pitching but not as he does before season, and everyone is different in their routine and preferences.