9 Reasons Roman Reigns Topped PWI's Top 500 Wrestlers 2016
4. Championships Won

The PWI criteria for championships won certainly fits Roman as well. On 22 November, 2015 he won the WWE Title against Dean Ambrose, and then was immediately screwed out of it when Sheamus cashed in his Money in the Bank contract.
A few weeks later he won the gold again, but was once again screwed when he was forced to defend it in the Royal Rumble and was forced to enter first. At WrestleMania, he again captured the belt, and then lost it once more by, you guessed it, being screwed out of it.
Roman held the belt on three separate occassions during the time period used, for a combined run of 118 days. So looking at it in a kayfabe sense, he may have never lost the title during that time period if given a fair fight every time out.
In Ring of Honor, Jay Lethal held their World Title throughout that entire time span, but perhaps PWI’s justification is that Roman had higher level opponents during that time...and they’re probably right.