If anything I would have thought the biggest age jump would have been between 10 and 11 since it seemed like 10 spent a lot of time roaming around the galaxy and time and generally going on his own merry way sans companions or at least companions we were told about. I mean hell he married 'Good Queen Bess' so... I mean let's face it, he could have lived with her for even the average life span of like 60-70 years - but its sorta quasi accepted that it was only a few years he spent traveling around
Time travelers are so funny that way. But what I find rather interesting really is that while he does seem to age - and frankly I have no problem with a couple hundred years passing here and there, but I do have a problem with basically the 11th being the "longest lived" Doctor of the bunch - with the exception of the 1st who - okay we're told he's the original - but you know Time Lord logic, "yes he was the first but first of what? First Doctor - yes. First me. No." Or for all we know the Doctor was his 'code name' before he took it as his real name.
Think fourth dimensionally. Personally a Doctor between 8 and 9 I dunno - 9 seemed pretty damaged so I suppose Hurt could have come from before his time - but at the same time - if it was 8.5 that put Gallifrey in Time Lock - and 'ended the war' then... why is 10 who basically KEPT the time lock intact not looked at as poorly - granted he died at the end of it all - but still. It was pretty clear the other Time Lords were pretty frickin' nuts and it wasn't such a bad thing that they're kept in Time Lock.
So I dunno... unless they're going to spring something and say that he was a time crisis dupe that sprung up and while he 'came from' the Doctor, he wasn't the Doctor and did some bad things... although what's more interesting. They specifically called the Doctor the Valeyard - who I thought everyone thought MAY have been an older form of the Doctor - although if that's the case - could the Hurt Doctor even be a POST 13 regeneration Doctor - like the Doctor had 13 regens and then thought he was dead for good and then Hurt pops out - saves the day doing something reeeally nasty maybe in the past - OR was the one that did the whole 'end the time war' thing... that resulted in the 9th coming around and somehow merged or was a memory echo... I dunno