Heading into the season, most projection systems had the Baltimore Orioles last in the American League East. Here at CBS Sports, our five writers had them pegged in fifth as well. There are still 157 games to go, but through one week -- MLB weeks are Monday through Sunday -- there is but one team in the majors without a blemish and it's these Orioles.

Though they did hit eight home runs, the team that was expected to be all power and very little starting pitching actually got some great work from its rotation.

Through one full start and one weather-abbreviated start, Chris Tillman has allowed only one run in seven innings with 10 strikeouts. Ubaldo Jimenez also only coughed up one run in seven innings. He struck out nine. Newly acquired Yovani Gallardo only gave up one run on two hits in five innings.

Through four games, Orioles starters were 3-0 with a 1.42 ERA and 23 strikeouts against only five walks in 19 innings.

On Sunday, Vance Worley put up three zeroes before allowing three runs in the fourth and fifth innings combined during a 5-3 win over the Rays. So he'll bog down the rotation ERA, but it still wasn't horrible, especially since the offense spotted him a four-spot in the bullpen was once again excellent.

Speaking of which, through five games, the Orioles bullpen has only yielded three runs in 21 1/3 innings (1.27 ERA). The lethal Darren O'Day-Zach Britton combo has gone seven scoreless but it hasn't just been those two. It's been a group effort in excellence.

As for the offense, there's been some good (Mark Trumbo, Manny Machado), some bad (Pedro Alvarez, J.J. Hardy) and a key injury to Adam Jones, though it's not serious.

That is to say that with some obvious regression coming from the rotation -- even the most ardent Orioles fans aren't expecting Tillman, Jimenez and Gallardo to combine for a 1.42 ERA this season -- the offense should be improving a bit as they move forward.

Now, some might question the competition. The Twins are off to their worst start in franchise history and have found a few different, let's say creative, ways to lose (notably Sunday). The Rays are 2-4. So the combined record of the Orioles' opponents is 2-10. Then again, five of those losses are from the Orioles. It's simply too early to say if the Twins and/or Rays are truly bad teams or just dealt with rough competition (the Rays actually split with the Blue Jays while the Twins had to deal with the Royals).

And that's the main takeaway here, well, maybe aside from never betting against the Buck Showalter Orioles. It's five games. It's too early to try to draw any sort of broad-sweeping conclusions about where the Orioles are headed.

In light of where many thought they were headed, though, that's a pretty damn impressive week. It does move the needle a bit, too, as the Sportsline projections now have the Orioles second in the AL East with a 52.5 percent chance to make the playoffs.

What a difference a week makes, right?

The Orioles are the only undefeated team in MLB.
The Orioles are the only undefeated team in MLB. (USATSI)