This is not realistic. Tony spent a week with Goggins - granted its largely wasted time, but its not why Tony is failing.
He visibly recoils from getting hit. The reaction he has to taking even glancing shots is big, overstated wincing in pain. Tony looks like he's moving in slow motion to boot and has poor athleticism, timing and durability.
Tony got old.
For his part, Paddy, who is an MMA adapted submission grappler, obliged him in a straight up kickboxing match. Paddy absolutely sucks at kickboxing, but he did it with nearly complete impunity because Tony is that washed. He was battering him with almost no fuss.
You can have Jesus Christ train Tony for a rematch, Paddy still mollywhops him in any version of the fight.