There's something called sarcasm. Sableye doesn't actually get Infiltrator lol.
Mega Heracross's problems are that its bulk, while better than many Pokemon (even some defensive ones), is not backed by Leftovers, and if it runs Close Combat it might as well not have the bulk. Without Close Combat, its only way through Steels are Earthquake and Arm Thrust. Arm Thrust is horribly weak and Earthquake is weaker than Arm Thrust, and doesn't really provide much meaningful coverage. It also cannot run any items to boost that Base 185 Attack. Its bulk is also not that great when you realize that its weaknesses, namely Flying, Psychic, and Fire, are very common in OU. It's not just Talonflame, but also Skarmory, Crobat, Alakazam, Latios, Latias, Starmie, Heatran, Charizard, and everything that uses Fire as a coverage move (pretty much all the Dragons, HP Fire Gengar/Alakazam/Latios/Latias) can force out Mega Heracross easily. Some of them can't switch in safely, but a slow U-Turn or Volt Switch can patch that, as can double switches.
Mega Heracross can also be walled. Its power is really nothing new (CB Heracross hits harder), it's just the coverage. Gliscor and Skarmory don't care about anything Mega Heracross can do, Steels in general wall it if it doesn't run Close Combat (Arm Thrust makes it gigantic Ferrothorn bait), and if it does it loses its bulk. Rotom-W can outspeed and WoW, it just can't take Bullet Punch that well. Intimidate in general neuters it, making it easier to take hits from it.
Mega Heracross is good at forcing mons out and damaging mons, it just has shortcomings. It's fine in B+ or B.