Did you see the size of that blister? It was over 1 inch in diameter. The trainer spread something over his foot too - it looked like Betadine which is something used to prevent infection over a moderately large area. He had to be in some kind of pain playing on that.
4 x IG Prestige MP, 70 cm, 376 grams, 386 SW, ALU Power @54, Prince Syn Gut 16 @58