"Towards the end of the year, we knew if we had [Harris] back in the side, we were going to be a little bit better side for that," Bellamy said.
"We gave him plenty of time to get his shoulder right, he's been really good for us the last five or six games that he's played."
Harris is one of four members of the Storm's title-winning squad that will be leaving Melbourne, after the 14-test Kiwis star signed a four-year deal with the Warriors in January.
Joining Harris in departing the newly-crowned NRL champions is Sydney-bound Melbourne legend Cooper Cronk, NSW State of Origin 18th man Jordan McLean, who is joining the Cowboys, and hooker Slade Griffin, who is expected to link up with the Newcastle Knights.
The quartet is the most of any premiership side since Melbourne's four lesser- known departees after their 2012 success, while champion fullback Billy Slater's future remains up in the air.
The losses also come after the Storm farewelled four players from last year's grand final side - including Kevin Proctor and Marika Koroibete - meaning almost half of their top team from the past two years have now left the club.
"I don't think that's happened to any club who has been in grand finals in consecutive years or been in grand finals two out of three years or two out of four years," Bellamy said.
"To lose eight players in two years out of grand final sides, that's not ideal. But that's just the way it is."
No team has won back-to-back premierships in a unified competition since Brisbane in 1992 and 1993.
- With AAP