Vert is obviously playing in OU, there's zero point speculating on anything else. Breakers are less clear. Their best OU starter this year was SoulWind, who would be at a strong disadvantage against Vert and I'm sure the team would rather flex someone else. stresh, JustFranco, and Nat all have cases. If the pick is Nat NU/Franco defense, then it's pretty clear. That said, of course, picking Nat NU tiebreak when the Shoguns have lax is pretty aggressive. You're saying "I don't care who you have, we're going with our best player and daring you to beat her." Reminiscent of the time the Classiest picked McMeghan ADV into a player that had already beaten him that tour (twice?) If you'd rather not make that play, Nat doesn't have an obvious place to flex into on defense, and I think you can reasonably make the argument that she's the Breakers' best OU player right now.
With that said, I think stresh is the obvious pick here for the simple reason that the Breakers are the ones that bought him. It's easy to look from an outsider's POV and say, well, maybe he's out of form, maybe he doesn't like the tier, whatever. Obviously you shouldn't be totally out on him after one rough season, but it's also true that he hasn't been super active for like two years. I can't speculate on what the Breakers know about their players' current form, either. But all I know is that this is the team that liked stresh enough to win the bidding for him, right at the start of the auction. Of all the teams that I think would believe in him to win a tiebreak game against Vert, I assume it's this one.
Noteworthy advantage the Breakers have in this tiebreak: despite Trichotomy's season, Shoguns PU seems like an unlikely option here because they'd probably have to deal with JustFranco on defense. The ways to take JustFranco out of the game on defense would be Ubers, LC, or DOU, none of which are happening. But honestly, on reflection they might have no choice.
Now, as far as the Breakers are concerned, I assume they want to find a way to get Nat, JustFranco, and stresh in there. Ann might be 7-3, but I just don't think DOU is ever happening. After stresh's season, I think you at least have to be hesitant about picking a tier for him, so defense or OU seems most logical. That leaves you with basically two attacking possibilities: Nat NU or JustFranco UU (I think Nat OU2 is mathematically real, probably forces either Nat-Axzel OU and lax-Franco lowtier matchups. That seems worse than whatever else the Breakers can force at first glance, but I'll come back to it)
Breakers NU: This is the route where you just go in guns blazing and bet Nat to win the rematch with lax. In this world, the Shoguns can either pick a lower tier into JustFranco (likely PU or RU, but I don't feel great about either), pick one of the other tiers (likely ass), or force JustFranco to play someone in OU. That someone is likely Axzel, although the hypothetical CTC play would be the hype one. In this world, I think the Breakers would be very happy; you have your best player in a tier she's 8-2 in, in a H2H she's 2-0 in this season, and you're arguably favoured in your defense tier. Why would you not go this route? Well, because lax is good! You definitely do not need to stretch to hard to see, like, Nat-lax and JustFranco-hjkhj/Trichotomy as a pair of even matchups, and then Vert is favoured. What else can you do?
Breakers UU: You get a guaranteed matchup that the Shoguns are not, on paper, equipped to defend. Putting lax there is Franco favoured, using lax for the most obvious attacking tiers (OU and NU) will just get the Nat matchup, picking some other random tier means that the Breakers can just swap Nat into UU and have Franco defend. Something like something like lax-Nat OU/NU + JustFranco-Sabella? UU is just the above scenario but better for Breakers. If the Shoguns try to force Franco off of UU with something like PU for Trichotomy, you get lax-Nat UU and Trichotomy-JustFranco PU, something like that? Lowkey, I'm not sure if that's better? Alternatively, could the Breakers prefer Vert-Nat OU, lax-JustFranco UU, and Trichotomy-xavgb PU?
Regardless, you can kinda see the thought process. If the Breakers pick NU, then the Shoguns likely just use lax there (the alternative is, what, feeding someone to Nat and then picking lax-JustFranco OU? is that even favoured?), and so you just pick your strongest slot knowing that Franco will likely be there. And if the Breakers pick UU, you still don't have an obvious tier to attack with lax that wouldn't get defended by Nat, so you try to force Franco to defend by picking a different low tier. Honestly, flip a coin. I think the Nat-lax rematch is very likely and the Breakers basically get to pick the tier. Personally, if I'm the Breakers, I'd rather NU.