I don't have enough evidence for statistical rejection or acceptance, but I've been op-upgraded both using online check in and airport check-in. Since I can't OLCI using my AA/Emerald status, I can't specify if my airport check-in op-upgrade has been influenced by my status, but I gather it has. However, I've even been upgraded using OLCI when flying MPC Green, so I cannot make any confident predictions one way or the other.

In other words, I don't know!