No.
Let's put this in the best case scenario for Achilles: Ben doesn't know about the heel. Lets look at what Achilles has as an Ancient Greek warrior. He's armed with a bronze sword and a bronze tipped spear. Ben's made of living rock. He's not doing to be doing much damage with those weapons. So he's not going to be putting Ben down like that. His bronze armour, though forged by a God isn't likely to stand up to The Thing for long either. Inside the box, Achilles is screwed.
So, let's look beyond that at other skills Achilles is likely to posess. He's going to be at the limits of human strength, endurance and athleticism because Myrmidons strike me as the type of people who train like insane motherfuckers, and also he wears heavy armour and runs around in it. However let us consider the implications of Achilles divine durability. Muscles are actually considerably stronger than whey are able to show. This is because the human body would literally tear itself apart if the muscles used 100% of their strength. Tendons, bones and the muscles themselves can't take it. For Achilles though this isn't an issue. He can't be injured anywhere other than one ankle. It is reasonable to assume that he's able to demonstrate Superhuman strength because of this. However, he's not going to be in the league of Ben Grimm, and he's going to have trouble doing any damage to his rocky form.
We must also assume that Achilles is skilled at Pankration (ancient Greek MMA, essentially) as this was expected of all soldiers at the time. The art combined aspects of wrestling, boxing and no rules (save no eye-gouging or biting) to create a violent sport in which deaths of the loser are not unheard of. If Achilles could lock Ben in a hold from which he could not escape, I would consider it to be an incapacitation victory. However, Ben's also got training in martial arts that are useful in this area as well. Combine that with his size, weight and durability advantages and it's an easy win for Grimm.