Within a small sample size, scoring does not define a player as "good", just like not scoring doesn't define a player as "bad". I realize that we're talking about someone looking "tired", but it's really the same argument. I haven't seen much out of Jagr (even when not scoring) that leads me to believe he's worn down or tired. Outside of an injury, coaching staffs regularly look at the whole body of work, not who's hot and who's not.
I'll give you an example of when small sample size becomes a problem. I coached a game this winter, we were up by 1 with less than 2:00 left in the 3rd. One of my F's took a penalty. My top two penalty killers are not great hockey players, but they are supposed to understand their role, move their feet, and clear the puck on the PK. One F creates a turnover inside our blueline and chips the puck out. He regains the puck and streaks down the ice 1 v 2 rather than dumping and changing. The D-man on his side of the ice trips while pivoting and my F shoots and scores from the circle, a pretty nice SHG....except that his decisions leading up to the goal were terrible and, in the long run, he would give up far more to the PP than he would be helping the PK. We won the game and he returned to the bench quite proud of himself. I was rather disappointed with his play, regardless of the fact that he scored.
As a coach who relies on the "eye-test" quite a bit, I caution you to think that because Jagr wasn't scoring or picking up assists that his play had dropped off.