For me, JJB came into his own in the 2007 season, and really stood out as an attacking player that year and for the next two years or so, to the point that he was outshining the likes of Lauitiiti in a lot of performances. After that IIRC he became more of a workhorse (and occasional penalty machine). 2007 was also the year when JJB grew the beard, and Jamie Thackray was famously axed because he wouldn't work on his poor ball-retention in training.
Another season that sticks out is 2006 - another underachieving year, despite Peacock signing. JJB was played at prop in some games by Tony Smith and didn't really make an impact.