The New York Yankees are off to a hot start to open the 2017 MLB season, but are they for real?

Before the Chicago White Sox took them down on Tuesday night, the Yankees had won eight straight games. The last time the Bronx Bombers started the season off this well was 1998, when they won 114 regular season games, the World Series and put their hat in the ring for the best team in baseball history.

As always this early in the season, there are catches — reasons to make us believe things aren’t as rosy as they might appear.

The bulk of this winning streak has come against bottom-dwellers: they swept three-game sets from the Tampa Bay Rays and the spiraling St. Louis Cardinals, both at home. The only team they’ve played that’s above .500 is the Baltimore Orioles, a series in which they dropped two of three.

The starting rotation is also a point of concern. Coming into the season, Masahiro Tanaka was viewed as the only starter close to reliable, but the staff has survived, putting up a 4.17 ERA and letting the bullpen do the rest. While Tanaka will almost certainly right the ship after a rough start, the rest of the rotation remains dotted with question marks.

In recent years, Michael Pineda has been the Yankees’ version of Anthony Kennedy if you will — the starter upon whom the fate of the rotation tends to reside. His two starts during the recent streak —  including a no-hit bid that went for over seven innings — were brilliant. But there’s skepticism as to whether this can continue. We’ve seen this from Pineda since the beginning of his career when he dazzled the league as a rookie with the Seattle Mariners. He earned an All-Star bid in 2011 before falling apart and and giving up a 5.12 ERA in the second half of the same season.

Yankees Michael PinedaA quick glance at Brooks Baseball shows that Pineda’s cutter is the catalyst for his strong performance this year and it may not be sustainable. Opposing hitters are batting .273 against it compared to .347 last season and .328 in 2015. They’re whiffing nearly four percent more often with an ISO nearly .200 points lower. This, my friends, is small sample size theater, and against struggling teams at that.

Same goes for CC Sabathia, who’s putting up a 1.47 ERA thanks to a .204 opposing batting average on balls in play. If you take fielding out of the equation and regress home run per fly ball rate to normal, Sabathia’s xFIP is 4.23. Those are bad omens and we haven’t even gotten to the bullpen.

While it will likely still end up one of the better groups in the league, the Yankees’ bullpen is performing at an unsustainable level as well. They’re currently allowing a .260 BABIP, 40 points better than league average, and stranding 85.2 percent of runners on base.

Both numbers are doomed to regression.

This early in the season, you can find cases for regression in either direction with any team you want. With a sport as numbers-driven as baseball and with such a small sample size, it’s tough to look at early-season totals as anything but smoke and mirrors. For example, you could make the case that New York’s offense is underperforming thanks to poor hit clustering.

However, on aggregate, it’s clear that the Yankees’ pitching staff is overperforming.

It may be that the team ends up a contender. Catcher Gary Sanchez has missed the streak and won’t be back from injury until May. Ditto for shortstop Didi Gregorius who has missed the entire season. Both will make the lineup better, and first baseman Greg Bird broke out of a slump Sunday night, going 3-for-3 with a double and a home run.

Long-term success, however, will continue to depend on pitching.

The team’s upcoming road trip just got a little easier with Pittsburgh Pirates outfielder Starling Marte’s suspension (more on that here), but the Yankees are about to run the gauntlet.

After they finish up with the White Sox, they go to Pittsburgh then Boston before flying home to play Baltimore. They get a quick break with the struggling Blue Jays, then head to Wrigley Field to play the defending world champs.

If they come out of that stretch as they came in, we know the Yankees are for real. But until then, this hot streak should be taken with a grain of salt.