There is prominent trend that Terran favor upgrade in their macro oriented builds for TvP. 6/7 of the TvP match ups that use a Reaper opening (any variation) opt for early upgrade (except Flash vs. Sora). This is no coincidence.
Background
In order to appreciate the current upgrade trend, it is important to have an understanding of the background of the metagame evolution.
Reaper opening has been invented early in Heart of the Swarm to replace the one barracks gasless expand from Wings of Liberty. As the game got older, more variations had been developed.
There are two main routes for a Reaper opening: Pull Scvs off gas and don’t pull Scvs off gas. The one that pull Scvs off gas is essentially a one barracks expand plus a Reaper. If you don’t pull gas, you will go for 1-1-1.
Last season
The 1-1-1 variation had been very ineffective since the end of 2013 season 2. The pulling Scvs off refinery version has been the dominant build for last season. Although the general idea of the build is set in sandstone, players come up with minor innovations to take advantage of the metagame. For e.g., plan an attack to force-trigger the photon overcharge to set up a bigger attack later. Or, you can choose a more go-for-the-face bio heavy style.
The Oracle buff shook the metagame. Protoss often opened with a one gate expand with a stargate follow up before transiting to a certain tech path. With the Oracle circling around the Terran base, it’s hard to move out of the base. Thus, the two mainstream styles of play mentioned above become less effective
Current upgrade trend
6/7 of the Proleague TvP games that used a Reaper opening so far had opted for the engineering bay before second barracks.
The current upgrade trend does not do anything drastically different. As I have already elaborated on the resource aspect of not pulling Scvs out of the refinery for the upgrade variation in my last post, I will not cover it here. For the record, it’s still possible that you pull Scvs off refinery for a quicker command centre, and put Scvs back in to line up the 100 gas for the upgrade (Maru vs. Zest). I will use the typical build for illustration purpose (Maru vs. Super).
10 – Supply Depot
12 – Barracks
12 – Refinery
15 – Orbital Command
15 – Reaper
To keep things simple, this build order does not pull Scvs out of refinery. Usually, if you go for a single Reaper into reactor and expand, you put down the command centre before the second supply depot. This is possible because you won’t get supply block since your barracks is building a reactor. However, since you don’t pull Scvs out of refinery to have the 400 mineral earlier for the command centre, you can build the second supply depot before the command centre to prevent the minor supply block. If you build a second supply depot first, it gives your scouting Scv the option to do an engineering bay block. The engineering bay will delay the command centre, which delays the second supply depot. This will supply block you. All in all, this minor difference does not affect the build.
17 – Supply depot
@100% Reaper – Reactor (Constant Marine production)
@400 mineral – Command Centre
@125 mineral – Engineering Bay (@100% – +1 Infantry attack)
@300 mineral – 2x Barracks
The traditional build will put down the second barracks after the command centre, so this is where the builds differ. I won’t go further into the build order as it is the same the traditional TvP builds. You get three barracks, then tech to reactor starport for Medivacs. After the +1 attack is done, start +1 armor. The upgrade start time of the stim and +1 armor should be approximately the same time. The second tech lab researches both combat shield and concussive shell. The sequence depends on opponent’s build order. If opponent went for blink Stalkers, get concussive shell first.
Why favor upgrade
It is better than other variations in the current metagame. Against Oracle expand opening, you have the option to build turrets due to the early engineering bay. The main value of this build against Oracle is that you are in a much better position when you move out. With the Oracle, you cannot really move out. Therefore, it is difficult to maximise the value of a bigger army early on from the earlier barracks. It then makes sense to spend the resources on upgrades early on, so that you have a better army when you can move out.
This variation is slightly better against two base blink stalkers. Protoss players prefer two base blink Stalkers build to the one base all-in version now. The +1 attack upgrade would have completed by the time the two base blink attack arrives. This helps.
Another TvP trend is that Protoss is starting to get an earlier third nexus. PartinG even took a third as early as 7:35 against Flash. Terran find it extremely hard to punish a standard quick third (around 9:30). This upgrade favor build aims to get the +1/+1, stim, combat shield and concussive shell, plus the first pair of Medivacs by 10:30. The third nexus becomes more penetrable. Watch how Maru brute force his way to take down the third against Super.
TerranCraft 
Hi Maxilicious thanks for the interesting post.
I would like to try the fast upgrade style myself. However I’m struggling with the execution. When do you pull out of gas? After you mined 100 gas for the upgrade and 100 for reaper/reactor? Do you know where I can find a replay of this?
What do you think about 2 or 3 barracks with this build? I think Demuslim used to play like this but with a 2 rax follow up. I’m not sure but 3 rax might do better against blink all ins.
PS: In one of your earlier posts you mentioned that you dislike Flahs’s 2 reaper opening. I’ve been doing that myself and I absolutely love it! You can split them up to scout the map very quick, and they can get some probe kills + it’s hard to deny your 6:00 scout.
I don’t have replays of these games, so I recommend you to click on the links in the post. If you’re interested in the timing to pull the Scvs out, you can refer to the Maru vs. Zest game. It is possible to apply everything even if you don’t pull Scvs out of gas. For easier execution, pull Scvs out of gas when you’ve 50 gas in bank when the first Reaper is building. Then, put Scvs backs in when you’ve 400 mineral to put down the Command Centre. Follow it up with an Engineering Bay, by the time it completes, you should have around 100 gas.
For this Engineering Bay before additional Barracks build, I think 2 additional barracks (3 in total) follow up is better than 1. Because
1. You want to catch up on the tech lab upgrades. You don’t want to start combat shield after stim.
2. The investment in the early upgrade means you have relatively less units for the early timings of Protoss. So more Barracks is not a bad idea.
I prefer the 1 Reaper then reactor build to the double Reaper build. It is because of the value of the first early Reaper. Protoss cannot deny scout against the first Reaper. If you get double Reapers, Protoss have Stalker and MSC when the Reapers are out. Although you can split your Reapers to scout for proxy, the delayed scout time more or less balance off the scout time of the early single Reaper.
How will this build fare against 1 or 2 base blink all ins? I see that you’re sacrificing an earlier barracks for faster upgrades.
If I’m right, the +1 attack should complete by the time a 2 base blink kicks in (haven’t examine it myself). It is hard for me to justify the trade off of quantity for quality though. Overall, there really isn’t a good answer for blink play now.