"It was a frustrating year," he said of his experiences in 2013.
His broken jaw came early in a match for his Northcote club, an opponent hitting him in a head-high tackle, but the glandular fever was worse.
"I think that was probably the toughest. With the jaw I could still get bigger [with weight training] but with the illness I lost all the weight and my fitness and I went back to square one.
"I knew this was a big year for me. I put some pressure on myself to stake my claim and prove I belong here. I concentrated on putting on weight and getting as fit as I could coming into pre-season and luckily it's put me where I am at the moment."
Hall has played a total of 44 minutes this season - all as a substitute, but Kirwan told him he was putting pressure on Weepu.
"I haven't had many minutes when I've come on. I felt a bit flat at the weekend but I wanted to do my best for the team. Luckily I got a few busts and breaks and got some running metres.
"[Kirwan] said I played really, really well, that I came of age; that's high praise that I'm really proud of."
Kirwan added of Hall: "He's really put us under pressure to pick him. I thought he came on and really made a difference. He was strong around the ruck, so for me it was Bryn delivering what we had hoped he would deliver. Piri's under pressure and we're under pressure to pick Bryn and that's what we want happening every week."APNZ