I'd concur. My anecdotal evidence, based on 30+ stays this year is that you get what you choose.

It's the gamble of getting a room that is acceptable vs. getting a comparatively worse room, or possibly a better room. I haven't scored a single upgrade this year (34 stays total so far) when checking in online. On the flip side, last night I moved hotels at the last minute due to no A/C in the original hotel, arrived 1.5 hours after booking through the HH Diamond line and as a Dia walk-up, scored an upgrade without even asking. As I said my experience is anecdotal but I think OLCI is working against me.....