Griffin did not sign Mozgov to a huge contract. LA did that. Griffin traded for Mozgov and Mozgov was a critical element to Cleveland's first Finals run. He did not re-sign him after LA massively overpaid to get him. And JR was one of the most important players on their championship team and was signed in the summer of 2016 when all of the contracts signed that year were inflated such as the ones we gave out to Moore and Hill.
Even if LeBron were healthy this year, I don't think anyone believed the Lakers had any chance to be more than a 2nd round exit in the playoffs, and even that is being highly optimistic. They were never considered to be a real threat in the playoffs and that is a big leap to make. LeBron missed 13 games in his first year back in Cleveland and most advanced metrics considered it to be a down year for him and that team still nearly won the championship (Kyrie and Love did not play in the Finals and it was 4-2). The team he was surrounded with was very good and were MUCH better than last year's Cleveland team. They eventually beat the greatest regular season team of all time eventually. If KD doesn't change the NBA by signing with the Warriors, they may have won another championship or two for all we know. It's also worth mentioning that Griffin left trade proposals for his successor to acquire Butler or PG13 for Kevin Love in 3 team trades that may have completely changed last year's outlook (https://www.cleveland.com/cavs/index...hind_prop.html). Obviously GSW would still be the massive favorites with KD there, but if LeBron and George are on the same team, maybe LeBron stays? Maybe Griffin would hold onto Kyrie and would have tried to make it work? The mistakes made by the Cavs FO after Griffin's departure should not blemish the great job he did there.
The main takeaway I have from Griffin's time in Cleveland is that Griffin is very much aware of the inner workings of locker room chemistry and is a strong relationship builder. He knew what LeBron needed and from listening to him talk about other players, he understood how everyone would be able to fit into their role and did a great job building a family in Cleveland alongside LeBron. Something I think we'd agree on is that Demps has seemingly done a poor job at communicating with his players over the years and there have been many players that have said as much after free agency (Cousins, Rondo, EJ come to mind immediately but there's probably more). Griffin has a great reputation among players and I have to believe that is not insignificant. I think one of his strengths would be to identify what is needed in unique situations based on the personalities at hand.