OAKLAND -- Given the typical home-field success experienced by A’s clubs even in down years over the past decade, manager Mark Kotsay had reason to chalk up his team’s inauspicious start at home this season to it being a small sample size.

The calendar has now flipped to June, but the troubling trend at home remains.

Falling to the Red Sox, 7-2, in Friday night’s series opener at the Coliseum, the A’s have dropped 18 of their last 21 games in Oakland. Now holding an MLB-worst 7-21 record at home, the A’s are off to their worst start through the first 28 home games of a season in Oakland history. Since 1901, there have been only two instances in which the club had such a rough beginning at home, once each when the club was located in Philadelphia and Kansas City.

This A’s team was always expected to take a step back from its postseason-contending ways over the past few years after trading away a bevy of stars this spring, so an underwhelming record is not exactly a surprise. Still, there does seem to be a clear gap between their play at home and on the road, where Oakland maintains a .500 record at 13-13.

So what could be leading to such dramatic home-road splits this season?

“I think this team thrives on the road, personally,” said A’s starter James Kaprielian, who took the loss Friday after allowing four runs over 5 1/3 innings against Boston. “I think we always have, at least since I’ve been here. The Coliseum is a big stadium and we don’t always get a huge fan base. That is what it is. I think when we go into other ballparks, we kind of feel an everyone vs. us type feeling. I think the guys do a good job of sticking together and embracing that energy on the road.”

The A’s were hopeful that an expected larger crowd for Fireworks Night on Friday at the Coliseum -- the announced attendance was a season high of 17,852 -- might provide an extra boost. Those hopes quickly dissipated, though, with Oakland’s offense mostly stymied throughout the night against Nathan Eovaldi and the Red Sox bullpen.

Of course, these A’s refuse to use the crowd at home, however big or small, as an excuse.

“It doesn’t matter,” Kaprielian said. “We have to be able to play and win games at our home ballpark. It’s nothing to do with fans or no fans. I just think we embrace that energy on the road pretty well.”

Perhaps the most surprising discrepancy between home and road has been on the pitching side. The Coliseum has historically been viewed as somewhat of a safe haven for pitchers, with the spacious foul territory and propensity for the ball to travel less at night affording them a chance to get away with more mistakes than they would in other ballparks. A’s pitchers hold a team ERA of 4.70 at home -- second-highest in the American League -- as opposed to a 3.58 ERA on the road.

Hitting-wise, Oakland is hitting .203 -- lowest home batting average in the Majors – with 76 runs scored at home compared to a .220 batting average with 105 runs on the road.

Jed Lowrie, whose two doubles Friday moved him into a tie with Mark Ellis for eighth-most doubles (204) in Oakland history, knows better than anyone about the difficulty of hitting at the Coliseum as he goes through his seventh big league season with the A’s. Breaking down what he saw from the offense against Boston, he noted a pair of balls hit by Sean Murphy and Kevin Smith as examples of how this ballpark can drive a hitter crazy at times.

In the fifth, Murphy roped a ball 103.3 mph off the bat with an expected batting average of .910. Smith came up right after Murphy and drove a pitch from Eovaldi with an exit velocity of 106.3 mph and .780 expected batting average. Both ranked among the 10 hardest-hit balls in play by either team, yet both were outs.

From his experience, Lowrie has a pretty good idea of what makes the Coliseum such a frustrating place for hitters.

“Sometimes the ball seems to carry decent and sometimes it doesn’t,” Lowrie said. “I’ve always found that, to right field, that wind kind of blows across and in. I’ve noticed that balls that I hit to right, it has to be at a pretty hard exit velocity with a pretty ideal launch angle to kind of cut through that wind. You see those flags up in right field by that little tunnel and it looks like the wind is blowing straight out. But the rest of that wind not going through that tunnel is just whipping through the stadium and going back the other direction.

“There’s balls that, quite frankly, work in other stadiums, in terms of hits, that don’t here.”

How do the A’s work around such a hurdle?

“You just have to find a way to get your hits,” Lowrie said. “That’s always been my experience here. Games are a little bit lower scoring and you have to find ways to keep runs off the board and put up enough to win.”