Gavin Rees has been a rugged and durable, world-class fighter during his career. He has consistently demonstrated a fearless commitment to forcing his way inside on longer fighters, then roughing them up.
The advantages of physical length in boxing are obvious, but a smart fighter can develop tactical strengths out of any unusual body type. A fighter as short as Rees can be a tricky target for a taller fighter to catch up to.
Rees is good at evading punches and then banging up his opponents when they have leaned into vulnerable positions, trying to reach him. As the more experienced fighter, that's the sort of mistake he will look to lure Crolla into.
Anthony Crolla has fought a very high level of competition on the domestic scene in England. He's been a professional fighter for almost seven years now.
He has put in the time in the gym and has tested himself under fire in championship-length bouts against some of the best professional lightweight prospects in Great Britain. In baseball terms, he'd be a guy who has had some decent success in AA and AAA.
It's probably not realistic to expect him to blossom into a superstar in the majors. But if the stars align, he's got the tools and knowledge to make something special happen for himself.