With last week’s additions of Troy Tulowitzki and David Price, the Toronto Blue Jays made themselves into a legitimate postseason contender, adding two of the game’s best players to a roster that was already pretty solid. Our rest-of-season forecast now has the Jays with the best projected winning percentage in the American League going forward, and while they’ll likely have to win their win into the division series through the Wild Card game, the Jays look like they could be a dangerous team in October. Price, along with bullpen upgrades Latroy Hawkins and Mark Lowe, gives them a good bit more pitching depth than they had previously, and Tulowitzki adds another quality hitter to a line-up that was already overflowing with offensive weapons.

But the more I look at this roster, the more I begin to wonder whether we’re overlooking one potentially significant flaw in this team’s construction, especially when it comes to the postseason. A week ago, when writing about the Tulowitzki acquisition, I noted that adding a good hitter to a good line-up could actually provide non-linear positive returns, above and beyond just that single player’s individual abilities, because getting guys on base leads to better outcomes for everyone else in the line-up. As I wrote then, we shouldn’t be too concerned about diminishing returns from the Blue Jays already having “enough” offense.

One aspect of the Jays line-up I didn’t talk about enough, however, was the fact that you can have diminishing returns based on line-up construction. Specifically, if you line up too many hitters from one side of the plate, your team will probably score fewer runs than would be expected based solely on overall batting lines, as a line-up that is dominated by same-handed hitters becomes a fairly easy match-up for the opposing manager in important situations. And while Troy Tulowitzki is an excellent player, the Blue Jays line-up may now lean too heavily to the right side.

Here is where the Jays non-pitchers stand relative to the rest of baseball in 2015 performance against RHPs and LHPs, to this point in the season.

This is a team that hits right-handers pretty well, getting a 107 wRC+ from their position players against RHPs, which ties them with the Astros for the seventh-best mark in baseball. But they absolutely crush left-handed pitching, running a 130 wRC+ against southpaws that is far and away the best mark of any team in the game; no one else is even really all that close. And this was before they added Tulowitzki, giving them another good hitter, but pushing their line-up even further to the right side of the spectrum.

In the regular season, where teams really can’t do too much to manipulate their rotation to exploit match-ups, Blue Jays hitters have only had the platoon advantage in 45% of their at-bats, the second lowest total in the American League; the league average is 55%. And that number is almost certainly going to be lower in the postseason. Here are the 2011-2014 rates for how often a hitter has had the platoon advantage in the regular season and then in the postseason.

Season Regular Season Postseason Difference 2011 54% 49% -5% 2012 55% 54% -1% 2013 56% 51% -4% 2014 55% 51% -4%

With more frequent off-days and higher stakes on the outcome of each at-bat, managers are simply able to play the match-ups more frequently in October than they do in the regular season. Ask yourself this: if you were an opposing manager facing the Blue Jays in a postseason series, and you saw a line-up that ran out seven right-handed bats alongside Justin Smoak and Ben Revere, why would you ever throw a left-handed pitcher against them?

Among likely AL playoff opponents, the Houston Astros are really the only team that wouldn’t be able to avoid playing into the Blue Jays strength, as their two best starting pitchers (Dallas Keuchel and Scott Kazmir) are both southpaws. Match-ups or not, the Astros aren’t going to bench those two and go with inferior right-handed pitchers, though you can bet that they’d likely be willing to go to the bullpen a bit earlier in that series than they would against other teams.

But everyone else? They can essentially throw a never-ending string of right-handers at the Blue Jays in October.

The Royals feature one left-handed starter, Danny Duffy. He could easily be replaced for that series with Chris Young or Jeremy Guthrie, assuming they don’t go pick up another serviceable #5 starter during the August waiver trade period. Their dominating bullpen is stocked with right-handed pitchers, and you can bet the Blue Jays would see a heavy dose of Kelvin Herrera, Wade Davis, and Greg Holland in a series against KC.

The Angels feature two left-handed starters, but with only a four man rotation needed in the postseason, there would be no real reason to give Andrew Heaney a start, meaning the Jays would only get one game against Hector Santiago. And like KC, their best relievers all run right-handed.

The Yankees rotation still has CC Sabathia in it right now, but the odds of him making a start against the Blue Jays in a postseason series are somewhere between slim and none. With Michael Pineda, Masahiro Tanaka, Nathan Eovaldi, and one of Ivan Nova, Adam Warren, or Luis Severino, the Yankees have more than enough right-handed starters to displace Sabathia. And while they aren’t going to shy away from Andrew Miller in high leverage situations, RHBs are hitting .078/.195/.146 against him this year. Miller’s 2015 dominance is even more impressive when you realize that 83% of the batters he’s faced this year have been righties, and he’s still been unhittable.

If the Jays do end up running down Minnesota for the Wild Card — and I think they will — they’re almost certainly going to be going up against the Angels or Astros in the play-in game. If it’s the Astros, you’d think it would be an advantage, because they match up well against Keuchel and Kazmir, but Houston is probably also one of the teams most likely to accept the fact that the Wild Card game should really just be a bullpen affair, making it a bullpen game instead. And so, realistically, they should probably be rooting for that game to come against Anaheim, leaving a potential Astros series for an ALDS or ALCS match-up where Keuchel and Kazmir would have to throw significant innings.

More realistically, though, the Blue Jays are just going to have to hit well against good right-handed pitching to advance in the postseason. They’ve created a line-up that strongly incentivizes opponents to stack up on sinker/slider RHPs, and they’re likely going to get a steady dose of guys who are in baseball primarily because they dominate right-handed batters. Because teams can adjust their rosters every series, and can allocate their innings to exploit match-ups more heavily, the Blue Jays are probably going to have the platoon advantage in fewer than 40% of their postseason at-bats, and maybe even as low as 25-30%; we simply can’t expect them to score runs in October the way they have been in the regular season, above and beyond the normal decline that comes from facing higher-quality opponents.

In fairness to Alex Anthopolous, there weren’t a lot of great left-handed hitters getting moved at the deadline. Nearly all of the good hitters who changed teams — Tulo, Yoenis Cespedes, Carlos Gomez — were right-handed, so it’s not like other teams were picking up the guys that the Jays should have been targeting instead. But I do wonder if the Jays overly right-handed line-up will become a problem for them in the postseason. Given the cost the team gave up to acquire David Price to push in on 2015, it might have made more sense to go for a better LH left fielder than Ben Revere, who isn’t exactly going to punish anyone for leaving a right-handed specialist on the mound.

The Blue Jays have a good team, and their right-handed hitters are still good hitters, even against right-handed pitching. But they aren’t as good as they are against left-handed pitching, and I wouldn’t expect Toronto to see many southpaws in October. If they get bounced early, line-up balance may end up being a thing the 2016 Blue Jays look to correct.