I've went through the DtB-Forum, the Established Decks Forum and some non-janky N&D Threads.
In the following threads the general consensus is "We slaughter Threshold":
Landstill, Armageddon Stax, MUC, Dragon Stompy, Ichorid, Skybus, Gargangel Stompy, Not Quite Survival, The Truffle Shuffle, TEC, Vaka Pox
In the following threads most players claim "We have a very positive Threshold matchup":
UB Reanimator, Tombstone, Vial Affinity, TarmoTog, Goyf Sligh, Death and Taxes
In the following threads most people tend to say "Our Threshold matchup is even to slightly favored, with the right MB/SB choices it can be pushed to 'positive'":
Deadguy Ale, MeatHooks, Dreadstill, MossNought, Karach, Cephalid Breakfast, Enchantress, Eva Green
In the following threads people actually talk about having problems with the Threshold matchup:
AggroLoam, Goblins, Combo Decks (Spring Tide, Solidarity, TES, Iggy Pop, Belcher, Fetchland Tendrils)
Therefore, the conclusion of a Source-reading format newbie would be:
a) Threshold has a bad matchup against almost every non-combo deck.
b)
Nobody is playing combo anyway
a) + b) = c) Threshold is horrible. Don't play it if you want to Top 8 in tournaments.
Historical Top8-Thread disagrees. Possible explanations of this contradiction could be:
1. People overestimate their pet decks, don't test the Threshold matchup properly and put up wrong numbers.
2. Actually Threshold is overrated, but since it is played by lots of skilled players who always win their bad matchups against scrubs and always reach Top 8, it's still a DtB.
3. Actually Threshold is overrated, but there are enough (combo-heavy?) metagames where it shines.
4. Threshold will soon fall off the throne of "the best deck in the format" because of the stated reasons. It'll just take some time.
Questions:
Which of those 4 explanations is true and to what extent? If 1. is true, which of the above listed decks should rather have a negative Threshold matchup? If 4. is true, how long will it take in your opinion? Also, are there other explanations beyond those 4?