Yeah, looking at his Destiel meta masterpost: http://andythanfiction.tumblr.com/post/50210715380/destiel-meta-masterpost-updated-2-15-14-no

I don't see anything with many notes. Looking at the ones in bold, which are according to him his "most popular ones or those I’m particularly proud of," I'm seeing 95 notes, 13 notes, 52, 173, 25, 73, 61...the majority of his ~200-odd meta posts are living in the 10-100 notes range. Here are the handful that got over 500 notes, but you can see that he peaked at 1500 even at his most general interest, wide appeal "Dean is bisexual" type meta:

605 notes: http://andythanfiction.tumblr.com/post/57846819541/why-cant-this-be-love
889: http://andythanfiction.tumblr.com/post/51981685436/stuck-in-the-middle-with-you-the-case-for-canon
697: http://andythanfiction.tumblr.com/post/49772946448/and-some-you-just-cant-tell
718: http://andythanfiction.tumblr.com/post/47917682184/seeing-you-for-the-first-time
886: http://andythanfiction.tumblr.com/post/46243577913/ac-dc
556: http://andythanfiction.tumblr.com/post/45938897525/dont-make-them-turn-this-car-around
1,694: http://andythanfiction.tumblr.com/post/43706382778/death-or-glory
1,572: http://andythanfiction.tumblr.com/post/42721086913/aint-my-bitch
1,311: http://andythanfiction.tumblr.com/post/42636543900/i-have-written-an-entire-meta-about-how-dean-has

And 1500 notes in a tumblr fandom like Supernatural is nothing, especially for the content he was writing. The really niche shipper conspiracy stuff? More likely to have 30-60 notes than not. He wasn't a big name meta writer in SPN fandom.