I think that's a slightly harsh way of looking at it. For me up to 2014 he did what any boxer would do working up to a world title and took fights that he could win in a fairly straightforward manner whilst getting himself up the rankings. He then won the title against Porter who is and was a genuine world level fighter. That win was his 11th professional fight. If you skip forward a couple of years to 2016 to date, he's had 3 losses against elite fighters (one of whom he had no business being in with weightwise, one of whom he for me stayed competitive with till his eye went and the other maybe being the #1 pound for pound fighter in the world at the moment) with tune-up fights in between.
As was suggested above it is that 2014-16 period that makes his record seem so shallow. He was hanging on for the big money fight with Khan and dodging the banana skins. I think if that pot of gold hadn't been on the horizon he would have had a really good chance of defending his title against legitimate contenders that would have looked much better on his record.
As others have said above - it's a cautionary tale for Callum Smith.
As an aside is it still him and DeGale the last two British boxers to win world titles in the US?
You make some good points Sammy, but I don't think it is harsh. I feel that it is a solid way to analyse a boxer's career in what is an industry filled with padded records and other assorted nonsense.
Porter was Brook's 33rd professional fight! His 11th professional fight was against someone called Geraint Harvey who had a 3-26 record. Also, Brook fought someone called Ernie Smith three times in his first 10 fights for some reason. Smith was 11-80-3 first fight and 13-97-5 in the third fight.
His level of competition only went up towards the 20 fight mark, which is fairly standard to be honest. Porter is a good fighter no question, and it was a superb win for Brook. However, his only defences came against Jo Jo Dan, Gavin and Kevin Bizier. He had also been a professional fight for 10 years by the time he fought Porter. For me, there is no doubt that Brook took too long to make the step up as well as not taking on better quality fighters at that point. His career will go down as a 'what might have been' for me, because I think Brook WAS a very good fighter indeed.
I would have favoured him heavily against Khan, but his nemesis has had the better career in terms of who he has beaten IMO. Khan has beaten the following:
Marcos Maidana
Marco Antonio Barrera (The Ghost Of)
Andriy Kotelnik
Paulie Malignaggi
Devon Alexander
Paul McCloskey
Zab Judah (The Ghost Of)
Chris Algieri
Luis Collazo (The Ghost Of)
Not exactly a Hall of Fame resume but still, overall, a better level of competition than Kell.