Hmmm, well I didnt mean to make it sound like Delver VS Oath was unwinnable for Delver. I agree it can go both ways game one, but that is a very general statement. I will be more clear with why I think it is an up hill battle (Not impossible) for the Delver pilot. These points will apply to a powered or non-power deck.
I've tested the matchup more than any other(except perhaps for the mirror) and if the delver player has enough hate then it is an uphill battle for the oath player. Once you take out their oaths, they become an awkward Bug Control deck that will get completely outdrawn if it can't land a Jace or Show and tell.
1-Oath is packing a full set of Mental Misstep, and one Toxic Deluge.
Hopefully the delver player is packing a playset too. The toxic deluge is irrelevant as long as you don't overcommit, because Delver can completely outdraw Oath in the long game.
2- The best open you can have is land, Delver, with Lotus Petal for like a Brainstorm, and hope you have Force + blue card. Most of the time you are just happy with a turn one Delver + Force back up. This is exactly what the Oath pilot wants. Now all they have to do is find the Oath.
I wouldn't call this the best possible hand, because it gets screwed over by misstep. This is a fine hand against Oath, especially game 1, but you don't need a threat in your opener. If you have a hand of wastelands and a threat, sure be a tempo deck, but for a majority of the time you will be a control deck against them, which allows you to side out some creatures for hate.
3- Delver wants to make their opponents life 0 as fast as possible. Getting a 7/7 flying lifelinker, is very hard to get past.
This is not always the goal of delver. Delver is not a straight up aggro deck like you make out to be. Obviously if they get griselbrand they will win, which is why your goal in the matchup is to prevent them from getting it into play. If the above statement was true Delver would be running swiftspear and price of progress.
4- Game 2-3 the hate for Oath is all 1 cmc.
This sounds bad in theory, but from testing the matchup I've found that getting blown out by misstep rarely happens.
Tarmogoyf I think is a bad choice because it plays poorly with Treasure Cruise. (I would never take out a Delver main, it is the key card that makes this deck powerful; Delver is the ideal open)
I agree that it can be hard to stretch to the 4th color in a field with Wasteland. Deathrite Shaman helps to fix this problem. I could explain all the problems that DRS fixes, vs Dredge and Shops but that would take 4~ever.
I can see why one would think Goyf would play badly with Cruise on paper. In practice, it doesn't. You can selectively delve, and the graveyards of your opponents will fuel it too. In many matchups, Goyf is better than Delver. Pyromancer is usually better too. Delver is by no means the key card that gives the deck its strength. That might change if the meta became filled with Combo and merfolk, and a variant of legacy style-Rug or Ur aggro became good, but for now the two drop threats do the most work. This is not to mention that the array of cantrips, cruises and gushes mean that Delver outdraws the majority of decks in the format.
If you want an example of when Delver is weak, it is when the deck is trying to be a control deck. When that happens, Delver is on the weaker side because it can only really do one thing, attack. It can trade with a two power creature, but that isn't always optimal. Tarmogoyf and Pyromancer, on the other hand, while excellent aggressive threats, can act as a moat until you gain control of the game and can finish them off.
The key problem with Delver then, aside from dying to everything, is that it locks you into one role. This is not Legacy Delver where you just want to tempo them out. The unique nature of Vintage means that it is often necessary to outdraw your opponents and grind them out. This is why I think the third golf is better in the main than the fourth delver.
I am aware of what Deathrite does in those matches, I've tried almost everything. I'm not saying adding the extra color is wrong, but I am warning that when you don't draw Deathrite early and they have wastelands you are in for a tough game.
