Allen at 18 has arguably the best change up in the Mets system. His fastball right now is only 90-91, but it may pick up some 2-3 more mph as he gets older. Right now he is projected as a middle of the rotation guy and has the upside to be better than that.
Rustich has the best Slider in the system and a 95-97 mph fastball. He also has a good chnage that has downward movement. He has 3 pitches that may end up being plus pitches. He is projected to be a 3 or possibly a 2 or even a closer. His problem and downfall may end up being his injuries.
Mejia who also is 18-19 and already throws a mid 90's fastball has a solid arsenal, He just needs better control of them. He is also projected to be a middle of the rotation guy, but he may end up being better than that.
Holt has a great and the best fastball in the system, and while his other pitches have come along according to some reports their still not plus pitches. He may end up being the Mets closer of the future eventually, but I hope am wrong and he does develop into a top of the rotation guy. Still at best right now he may be a middle of the rotation guy.