Cancelled or bowed out--doesn't really matter to me--BSG had a stellar first season-tightly written, epic storytelling, heavily serialized, urgency of purpose. Then the last 2.5 seasons it was all over the map. It really could have cut out a lot of crap and merged seasons 3, 4 and 4.5--trimming a season and a half out.I always got the impression (my own opinion mind you) that Moore and company decided to end their show at Season 4 to avoid cancellation. BSG's ratings were probably at their lowest point before Moore's decision. It was a prestige show for Sci-Fi so they likely didn't want to cancel it but at the same time the ratings were so low, they might have had to eventually. Deciding to end the show at Season 4 allowed both sides to save face.
I mean we had the tedious love quadrangle, the Baltar cult that just dragged on, the stupid Six/Tighe/Ellen triangle, the stupid Six baby plot, a whole bunch of uninteresting filler, the mythology just fell flat at the end. The only thing that salvaged it was a stellar series finale in "Daybreak".
Eccelston was okay in his role but hardly vital to the series. The real reason "Company Man" was good was for Noah. Matt and Ted were also good. Claire wasn't horrible as per usual. The writing was smart for a change. And it wasn't a stand-alone episode - it was part of the overall arc, like all the episodes were. My favorite is still "Five Years Gone."