Please remember that this is a rumor and as always some salt is required. While the rumor may contain some speculation as to a release time frame, its is rather logical given the 25th anniversary and normal time for specialist game releases.
I know it's been a good while since we had any rumours of a new Blood Bowl release and I'm not sure if this is common knowledge, but I thought it might be worth sharing.
I was chatting with a member of staff in my local GW about starting a Blood Bowl league with some friends. The staff member in question strongly advised me to "hold off on that" and said to expect "a bunch of new models" this year as it's Blood Bowl's 25th anniversary.
They couldn't (or wouldn't) say exactly when to expect it, nor could they give more details, just that it'll come before the end of the year. I would guess around September/October if Space Hulk and Dreadfleet are anything to go by.
I don't know how useful this morsel of information is, but it is at least a separate source for the 'new Blood Bowl this year' rumour.