The only position in the top eight still up for debate is eighth place on the ladder as the Raiders or Broncos will round out the top eight.
The result means 2022 will be the first time since 2014 the Storm will miss the top four, a result CODE Sports' Lachlan McKirdy tweeted.
And since 2006, including the 2010 season when the Storm was last as punishment for its salary cap scandal, it's just the third time in that period the Storm have finished outside the top four.
Speaking to ABC after the game, Storm hooker Grant said: "It hurts a lot, obviously ... going into the finals, a couple of losses, and the position on the ladder really hurts ... looking forward to going to training to fix a few things."
Cameron Munster was equally despondent after the game.
"I was pretty poor tonight, I thought I was good in glimpses but I pretty much let the team down tonight," he said on Channel 9.
"It was a big game for us and... I can't explain pretty much what happened. The back end of the game we showed what we can produce but it was just that first 20 to 25 minutes there."
The Eels were dominant for much of the match, leading 20-0 after 62 minutes before the Storm launched a fightback.
Tries to Harry Grant, Nick Meaney and David Nofoaluma cut the lead to eight points with just over a minute remaining but a missed conversion from Cameron Munster sealed the result.