Weavile is B Rank material but not A, it's frailty and Stealth Rock weakness really drop against it. Not to mention the abundance of Fighting types roaming in OU. Mach Punch is a quick and easy answer to it. Scizor also is King of OU usage, which Weavile can do nothing against it, but Low Kick on the switch. Yea it's Stabs are amazing, but still only niche amazing. Most Steels can easily shrug a non-stabbed Low Kick and KO.