During the last eight years of my coaching, I was part of a group that serviced and evaluated pitcher’s coming off injuries of all kinds. Here’s what I see.
See the way you raise and stretch out your pitching arm after every pitch - this is an involuntary response by your body to “reset” your arm. Now that word that I used, " reset" is my language and my language only. Basically, your body is telling you, without any deliberate decision(s) on you part, that stretching that arm feels good, to the extent that if you didn’t you just wouldn’t be in shape to use it again the way you want. Also, for a guy that came off a bad case of tendonitis last year, you’re really bringing the heat. (that’s a compliment)
Tell you what - the next time you get in a bullpen session, do this. After warming up properly, start tossing at half game speed just to get the range and feel of your overall pitching cycle - to beginning to end. Then settle down a bit, relax, and prepare for five pitches at your normal game speed - four seam fast ball. Do no more than five pitches. After the fifth pitch, drop your glove on the floor and stretch out both arms with fingers pointing straight ahead.
Take special note of the hands. Your glove hand should remain some what steady - without shaking. Your pitching hand should also remain some what steady - without shaking. If your pitching hand starts to shake, you have the remains of your tendonitis.
One of the “tests” that a pitching coach will do for those pitchers coming back from such an ailment, is to greet that pitcher with and introduction and shake his hand. Nothing unusual here - right? But when the pitching coach grasps the pitching hand firmly, then slightly turns it like a door knob - any wince or facial expressions from the pitchers tells a coach - "you’re damaged goods son."
By the way, a coach not only does this for his protection and that of his contractors/ club, but also for the man himself coming off an injury.