Back to the original question....
I don't think you can compete at a high level without some sort of a moving pitch unless you have a truly exceptional fastball of some type to mix in with a good change. The difference between the fastball and change had better be so great that the batter cannot split the difference in anticipation, and then adjust as the pitch comes in. In other words, there has to be a minimum of 14-15 mph between the fastball and change.
There aren't many with that truly exceptional fastball. At low levels, velocity alone is enough. At mid levels, changes in velocity is enough. At the high levels, they are looking for location, movement, and velocity - in that order. I believe any pitcher is much more likely to compete with curve/slider.
A few years ago, there was a debate on the Marlins board about whether the members magically gained MLB talent, in a must get the ball in play situation, would they rather face Beckett's typically 95-97 fastball, 80 change, and 12-6 looney tunes curve; or AJ Burnetts 98-100 fastball and low 90s change (he has, since leaving the Marlins, been effective with a decent curve). Even in my dreams, I'd have enormous trouble with AJ's fastball, though his location was suspect. I said Beckett until unless I was behind in the count. If I was behind, I'd much rather face a relative known with AJ than face Beckett and not having any idea if I would be frozen by a fastball, made to look like an idiot with the change, or have my knees buckle with the curve.
I was thinking I'd seen Pedro throw several curves, especially in recent years, which TSN supports:
Assets Though he's lost a few clicks on his heater, he's learned how to use it better. You never know from the speed and angle of his arm when he's throwing a change-up that comes at you 15 mph slower than his fastball. Lefties can't do a thing with his curveball, which also comes from various angles.
Flaws Though he's gained some weight, he's thin and has to put his body through a lot to get a ball to the plate as fast as he does, which has a thing or two to do with his problems with nagging injuries. The few base-runners he allows find it easy to take second on him.
TSN