Just so we're clear, there are two kinds of "ORTG" that get thrown around. One is what is seen on nba.com/stats which is literally the team's offensive rating when that player on the court. The other used to (maybe it's still there) be surfaced on bball-ref and was an estimation of a player's impact on offense. It's basically win shares. In other words, it essentially useless. But people often compare often to oranges with these two things. The first calculation is the only one that has use.
Here are some numbers on Gobert's time with the Jazz:
The Jazz were better with him on offense six out of 9 years including six out of the last 7.
His offensive RAPM, which only uses lineup data and no stats and accounts for teammate performance, was positive his last 7 years with the Jazz....peaking at 21st overall in the league his last year with the Jazz.
His BPM, which uses box score stats to estimate RAPM, was positive his last 8 years with the Jazz and quite good throughout.
His EPM, which uses RAPM and box score stats, was positive all 5 years the statistic has been produced for.
