On Thursday night, the New York Mets completed a four-game sweep of the New York Yankees. It’s the first time since Interleague Play began in 1997 that the Bronx Bombers didn’t win a single game in the regular season Subway Series. The Mets had two comeback wins at Citi Field and never trailed in the two contests at Yankee Stadium.

Heading into the Subway Series, the Yankees had been one of the biggest surprises of the 2013 MLB season. Despite players like Derek Jeter, Alex Rodriguez and Mark Teixeira not having had a single at-bat, the club managed to lead the American League East through 49 games. Players like Curtis Granderson, Andy Pettitte and Kevin Youkilis have also spent significant time on the disabled list.

In their last four games, however, the Yankees were dominated by a team that started the series with the second-worst record in the National League. Is the current losing streak a sign of things to come for New York?

The Yankees managed to win 61.2 percent of their games, before the Subway Series. However, the team didn’t do so in a very dominant fashion. The Yankees made their way into first place by winning a lot of close games. They boasted the same or better record than five other teams that had a better run differential. A team’s run differential is one of the best indicators of how they will perform going forward.

As the season moves closer to the midway point, the Yankees luck on offense may be running out. Players like Vernon Wells and Travis Hafner, who haven’t performed well in a few years, are starting to regress to their recent numbers. In May, Wells batted .220, compared to his .300 April average. Hafner’s average and slugging percentage plummeted from .318 and .667 in the first month to .179 and .299 in the second.

The Yankees should improve as their star players return from injury. Jeter will be a major upgrade from Jayson Nix, who’s hitting .218 through 45 games, and Teixeira and Rodriguez will take at-bats away from guys like Hafner and Lyle Overbay.

Unfortunately for New York, the club doesn’t know when it will get all of its stars healthy. Rodriguez won’t play until after the All-Star Break, and general manager Brian Cashman hasn’t ruled out the possibility of him missing the whole season. Jeter is far from being ready to play and he won’t give a target return date.

The biggest hope the Yankees have to stay in the playoff race is with great pitching. Even in their recent losses, their pitchers have been strong, allowing more than three runs just once. New York’s bullpen has been one of the best in the league, and the most recent blown save by Mariano Rivera will be one of only a few this season. Hiroki Kuroda has pitched like a Cy Young candidate, giving the team three above-average starters, along with Pettitte and C.C. Sabathia.

Even with the losing streak, the Yankees would be in the playoffs if the season ended after the Subway Series. Their recent play, though, does highlight some concerns that could be an issue for the next couple of months.