Maybe cause the defense isn't been screwing up as of late. No?
It's not just D (or goalie-independent D) and you can look at MoneyPuck for the stats if you want to actually take a look.
NHL Goalie Analytics, Expected Goals, Expected Rebounds
moneypuck.com
Biggest difference between Gru and Daccord in all situations? Puck freeze rate (and not from a rebound perspective).
Daccord has by far the biggest difference between expected puck freezes and actual puck freezes in the NHL for goalies with a minimum of 10 starts. And furthermore, Joey and Gru couldn't be any different in this stat. Since they have virtually identical numbers for "rebounds per save," the most likely culprit is that Joey is much, much more active in playing the puck with his stick than Gru.
Joey keeps the puck moving when he has the opportunity while Gru tends to freeze it.
The Kraken are not a good faceoff team (23rd out of 32 in all situations). Would you rather have your goaltender freeze the puck for a d-zone draw or handle the puck and help the defense clear the zone? In the Kraken's case, avoiding that draw just a few times a game might be a better option.
It's possible that Joey's puck handling is helping Seattle's defense clear the zone... and that's an area the Kraken d struggled mightly the first quarter of the season.
It remains to be seen how the numbers play out the rest of the season but there is reason to believe that Daccord's puck handling is a huge benefit to Seattle's D.
(Daccord also has a higher SV% than Gru on unblocked shots and low-danger unblocked shots... as someone else noted, Joey is making the easy saves at a higher rate than Gru, so far.)