With their two big-time receivers - between 110 and 130 passes in their first four years, including guys who have hit that mark this year and haven't played four full seasons yet. If you want to exclude them, 21 guys have done it, and Douglas' four touchdowns are tied for the fewest (with 85 times in the past decade, but all of the names on the list, except one or two, are pretty big names. With an ostensibly mediocre first four years with no progression and an immediate jump, it's only natural to assume it was just a jump in volume, which led to a jump in his counting stats.
But a closer look into the metrics suggests he was getting slightly better and better as the years progressed.
The Look Inside
Douglas didn't stray far from his production in his first four years, but looking at his metrics after the fact, the breakout seems less surprising than it would have if you just saw his traditional stats.
Here are his five seasons worth of Reception to use tight ends primarily for blocking this season. Levine Toilolo seems a good bet to be a red-zone target, but that's not where Douglas excels.
It's not common, but it's not unheard of for the third receiver on a team to be fantasy relevant, which is why teams like the Packers can have three fantasy-relevant guys (and even the Dolphins can do it). If the Falcons keep up their high-volume passing attack and are as successful an offense as our math thinks they will be, Douglas may not need an injury to one of the top guys to produce this year.
He doesn't cost you anything in the draft, and he's got 80-reception upside if anything were to happen to a starter. Not many guys going undrafted have that sort of ceiling, but Douglas has proven it and so have his metrics.