How were they a play away from losing all 5 Super Bowls? The only ones they came from behind and could’ve lost were the Panthers and Seahawks.
I think they could’ve won more but could’ve lost more. For example, in 2011 had Lee Evans caught the pass in the AFCCG or the Seahawks not panic and throw the ball, they had a scare vs the Titans in 2003, and I almost forgot how the refs could’ve ignored the tuck rule.
But to answer the OP’s question, I’ve always been in the camp that the Pats have had weak LB’s since 2005. Secondary hasn’t been great either. But I think what has lost them more games than that was bad coaching decisions or flat out out coached on that day and players not executing. But more often than not, those coaches have to put together the perfect game plan and players have to play the game of their life.