They’re fullbacks, only fuller. Or loosely defined tight ends. The NFL’s newest offensive weapon, the H-back, is a handy and versatile threat that keeps the opposing team guessing. A cross between those two positions, H-backs can run, block and, increasingly, catch passes. Meanwhile, their mobility behind the line of scrimmage makes them tough for defenses to predict. That’s probably why teams are willing to pay millions to fill the spot, aided by colleges turning out leaner, more athletic fullbacks who promise to defy expectations as they take their positions.