The longer this goes, the more I think it means Berman is siding with Brady. If he were ruling for the NFL I would think his opinion would be short and not terribly complex, possibly just saying upheld and maybe citing a case or two of Courts deferring to arbitration in CBA agreements.
I don't think he would go through all of the NFLPA's arguments and try to cite why they don't apply with reasoning and cite cases on them.
If he is siding with Brady and the NFLPA he wouldn't just rest it on one issue, he would set a bunch of failures of the NFL to abide by the CBA and how each of them means the NFL can't win. That sets up a much more difficult appeal for the NFL because the Appellate Court then has to reject each of the points and that would be hard to do.
That would take his clerks a lot longer to fashion than simply citing a couple cases and saying the Court defers to the arbiter.