Why is Tim Lincecum pitching entire games from the stretch lately? Seems he would be giving something away with that.
Worked for Don Larsen. 
Working from the stretch can actually give away less. Less motion, less time for a pitch to be exposed.
There are a number of schools of thought that recommend only pitching from the stretch. Since a typical pitcher will have a runner or two on base every inning, most of the work he does in a game will be from the stretch anyway, so why the big change in delivery for what is a fairly minor advantage in a pitcher’s ability to pump up his velocity or hit locations? Better to just focus on the thing you’ll wind up doing most of the time anyway and perfect it. There are any number of relievers who only pitch from the stretch. The Doyle Baseball school out of Florida (run by former MLBers Denny, Brian, and Blake Doyle), for example, exclusively teaches pitching from the stretch.
I don’t really think he’s giving anything away pitching only from the stretch, aside from not getting to showcase his herky-jerky wind-up. Some guys can pick up a mile an hour from the full wind-up or maybe spot their pitches slightly better, but at the end of the day, once the pitcher’s front leg kicks up, the rest of the delivery is identical whether you started from the wind up or the stretch – stride and break your hands, land with your arm back in the throwing slot, explode forward to the target. Really not much to gain or lose either way.
Hadn’t noticed it with Lincecum, but maybe he’s just more comfortable with that. It’s also possible he may be trying to work on some specific part of his delivery that he or his coach find easier to accomplish from the stretch.
I never understood why relievers always pitch from the stretch, whether bases are empty or not. I was always much more comfortable with the wind up.
Wow, someone else has heard of these guys? I went to one of their camps back in the early 90s. They definitely had interesting theories on pitching and hitting. True, it’s all stretch all the time for pitchers. And they teach hitters to stand with feel about double your shoulder width (or more) apart and do not take any step at all with your front foot. That would definitely take some getting used to.
If you’re a guy who might be coming into the game in the middle of an inning with runners on base half the time, you might as well go with the delivery you’re as likely as not to be using. What I really don’t understand is when a reliever comes into a game with runners on and spends most of his warm-up on the mound throwing out of the full wind up – dude, you’re not going to be doing that; why prepare to do it?!?
Our league had some Doyle reps travel up here a couple years in a row in the mid-90s to run some weekend clinics for coaches and players. While I haven’t adopted everything I learned from them, I did get a ton of really sound material from their clinics. Stretch only for pitchers was unusual and no-stride hitting remains radical, but also makes a lot of sense in many cases. If I have a kid on my ball team with an overstride issue (which is all the time), the first thing I do to work on correcting it is to take the stride away from them so they can discover that striding is a timing mechanism and does nothing at all to improve their power, bat speed, or control.