Is Brook now a massive underdog vs Amir Khan? Weight?

Brook's weight issues, and how the new IBF weight ruling will effect him. It is widely known in the Boxing world that Ezekiel Brinsly Reid Brook (Kell Brook) is a massive welterweight. It is also a well known fact that Brook has had trouble with making weight, and even had the rematch at a catchweight of 152lbs with Carson Jones. However, lets give Brook the benefit of the doubt, and say that this was down to a lack of motivation for the Jones II fight, and that Brook was not sticking to his diet plan during the training camp. Now then,... Kell Brook normally comes in to the ring on fight night, at a weight between 163-167lbs. This means that Brook is cutting around 16-20lbs, to make the welterweight limit of 147lbs. Furthermore, Brook also holds the IBF Welterweight World Title, and the IBF have recently made a rule that fighters cannot weigh more than 10lbs over weight class limit. This means that Brook would now would have to weigh 6-10bs less, than he normally does, in his next defense of his IBF Title. How does this link in to a fight with Amir Khan? Boxing fans in the UK and around the Globe, see a Khan v Brook fight, as a 50/50 fight. Sky Sports, the TV Channel that telecasts all of Brooks fight, have odds for a Khan Win at 4/9 and a Brook Win at 7/4, so they see Khan as the clear favourite. I myself always saw the fight going either way, and have always said that Khan either wins on points, or Brook stops Khan, with Khan not being able to deal with the power, pressure and size that Brook applies. However, with Brook now not able rehydrate to his natural fight weight, he will clearly be a lot weaker weighing 157lbs than he did weighing 163-167lbs. This also means that he will have literally no size advantage over Khan, with them both being the same weight on fight night, both being the same height, and Khan with a 2" reach advantage. I personally don't see any fighter who has to weigh 6-10lbs less than he has weighed for his entire career, being the same fighter that he was at his natural weight, and therefore see Khan as the clear winner. (well you never know about Khan and his chin, but you know what I mean) Is now the best time for Khan to catch Brook? And is Brook now an underdog, as oppossed to a level opponent pre IBF weight ruling? What are your thoughts?