I'm not sure what kind of job you had linked to the honours system, but Beckham has not got a KBE. He's got an OBE, same as Murray currently has. It's also what Henman has, but he got his after he retired. The system is supposed to be cummulative, and reflect achievement/contribution over time - and it's for all sorts. There is a committee that specifically considers sports stars, but another for the arts, and one for scientists, one for business etc. There is a whole separate system for the military.
IMO, no active athlete should get an KBE or DBE, plus Andy is far too young. As funny as it would be for the umpire to have to refer to Andy as Sir Andy, it is unworkable, and he'd not be able to enjoy it.
Traditionally, there is an expectation of waiting five years between honours, but I think a case could be made for Andy to get the CBE (the order is MBE, OBE, CBE, KBE) in the next list. IMO, Leon should get something for everything he's done over past five years, and Jamie could get something for Davis Cup this year, as well as the two slam finals and his mixed-doubles Wimbledon win. Simply being on the winning Davis Cup team shouldn't be enough, but it gets complicated with team sports. All athletes who won gold at London 2012 were automatically awarded an MBE as a minimum, but everyone in a rowing crew rows the same distance, so I'm not sure that's the same thing.