I slightly disagree that Ryder made a "tactical error" In " taking the fight to Blackwell". I don't think that's what happened. I think what happened was that Blackwells workrate and pressure was starting to tell and Ryder saw close range as a sort of "safe haven"... It was the only part of his game that was definitely superior to NB IMO. But he was already starting to tire, and that in close stuff has a very fine margin for error. Even his initial sharpness slipping just a fraction, combined with NB starting to figure him out, time him and zero in with the short right " hooker-cut" took this "in close safety zone" ..which had previously been Ryders domai, away ....and contributed to the suddenness of the ending, with Ryder putting up no protest ...cos HE realised he was beaten.
We must agree to slightly disagree, Ryder would have done better by sticking the jab and moving more, but i still think Blackwell would have caught up with him , to me staying up close was not a good idea against Blackwell due to as you said the short right hook,ok against Saunders though but not Blackwell. I guess John thought he could as thats what he does