The guy that computed these stats is the same guy that said MHJ dropped one ball all year.
I think most of MHJ's drops are technically marked as pass breakups for the stat counters. But anyone who watched Larry Fitzgerald play knows those breakups were on Marv.
Has Odegard ever stated the source of his "one drop" stat for Harrison?
As far as I can tell, it's not a stat that's officially tracked by the NFL.
I've only found three sources that include drops among receiver stats, and none mentions where they get their stats:
Pro Football Reference shows 5 drops for Harrison.
FantasyPros also shows 5 drops.
PlayerProfiler.com (never heard of them before) shows 3 drops for Harrison.
Pro Football Focus also seems to track drops, but that column seems to be behind a paywall.
Certainly drops are a subjective stat, but I haven't found any sites that claim Harrison only had one drop, and my eyes tell me there were about 5 obvious and egregious ones.
He did seem to improve greatly in that department in the second half of the season, and ended up fairly far down the list in terms of drop % for the season.