Was just looking at some match records on profightdb
Seth Rollins and Sami Zayn have really gotten a bad shake. They've been put in terrible positions to have good matches.
Rollins won the title at WM35 and then we got a one-off with AJ Styles that was a great match-up. After that, he went into a program with Baron Corbin (sucks), had a quick thing with Lesnar again (actually had a really good match at Summerslam), but then went into programs with Strowman and The Fiend.
As for Zayn, he hasn't been as active over the last year (healing up from shoulder injuries I presume), but before that his most recent singles matches on PPV were with Lashley, Strowman, and Baron Corbin. He had a great feud with Owens that culminated at Battleground '16 with him winning, and they went nowhere with it!