Costa's X-Factor: Size and strength
Chimaev has fought in the middleweight division before, and if his horrendous failure to make weight for his last welterweight fight is any indication, this is the division he belongs in. However, he may find that many of the advantages he enjoyed as a welterweight do not exist at middleweight, particularly against Costa, who himself struggles to make the division's 186-pound limit.
Costa needs to use this to his advantage. He needs to throw all of his weight and power at Chimaev. He needs to bully his foe with such severity that the Chechen juggernaut begins to wonder if maybe it's worth enduring the brutal cut down to 170 pounds after all.
Chimaev's X-Factor: Momentum
In the early chapters of Chimaev's UFC run, momentum was his main claim to fame. He famously scored his first three wins in the span of a few weeks, and after that frenetic run, looked like he could be in title contention in a matter of months. The man was a runaway train.
But momentum is longer on his side. In fact, after rattling off his first three UFC wins in record time, it took him almost two years to collect three more wins, and it has now been over a year since we've seen him in the Octagon.
This isn't to suggest he will be a worse fighter in his UFC 284 return, but ring rust is real, and he may find his timing and reflexes aren't quite on the level they were when he was fighting every few weeks. That could be a problem against Costa who, as we've covered, is typically extremely aggressive.
