The IVs in Halo 4 were just one of the many failures of that game. This is true, but we must also keep in mind that Locke was a bounty hunter, and he was skilled enough to be singled out by ONI for recruitment. That shows something more than just your average ODST like Buck. Buck was picked for the fact that he was an ODST and survived some of the most pivotal battles of the war. If he were to go toe-to-toe with Locke, I'm pretty sure it would be a close fight, but Locke would emerge the victor.