It's not that he *never* dives, it's just that he quite often doesn't, of he does it's pretty poor.
Look at Blackburn, it's not a well struck shot and he's beaten to his near post side. He just didn't get any horizontal movement.
Fulham, his 'dive' again was very similar, he gets no horizontal movement and basically just falls over.
Two against Huddersfield, neither did he dive for.
Reading, he didn't dive for that either.
Then throw in things like Millwall where he's rooted to his far(!) post and doesn't claim a ball that's 3 yards out. We concede.
Throw in his mistakes from his distrubution or where he's failed to gather the ball...
How is SJ doing? Honestly? Not great.