OAKLAND — The Seahawks’ exhibition season began with Trevone Boykin appearing to have just about locked up the backup quarterback competition before it even really started.

It ended with the battle between Boykin and Austin Davis looking as muddled as ever, and the decision of which to keep looms as the Seahawks will have to decide by the time rosters have to be cut to 53 on Saturday at 1 p.m.

While Boykin threw two first-half interceptions and let the clock run out to end the first half when the Seahawks were in field-goal range, Davis led a late 75-yard touchdown drive to give Seattle a 17-13 win.

Davis was 5 of 5 for 67 yards on the drive, capping it by hitting Kenny Lawler with a 16-yard touchdown pass with 1:10 remaining.

“He’s right in the middle of the competition of it,” Seattle coach Pete Carroll said of Davis. “He’s done very well. He’s had good outings. This was really a great showing for him.”

That the backup quarterback spot was the main source of conversation said all you needed to know about the fourth and final exhibition game between the Raiders and Seahawks here Thursday.

Thanks to a new rule allowing teams to still have their full complement of 90 players for the fourth game, the Seahawks and Raiders played almost none of their starters.

Seattle’s only certain starters who played were on the offensive line with the Seahawks wanting to give that group one more chance to develop some continuity heading into the regular season (though left guard Luke Joeckel sat out after having Regenokine treatement this week). The line played three series.

Otherwise, it was nothing but backups and deep reserves and a combined 16 penalties seemed somewhat fitting.

With Russell Wilson among those sitting out, Boykin got his first start of any kind in his Seattle career.

He led Seattle to an early 10-0 lead, including guiding an 86-yard touchdown drive in the first quarter.

But he also threw two interceptions in the second quarter and finished a spotty 13 of 21 for 166 yards with one TD for a 62.9 passer rating in playing the entire first half.

One interception came when he overthrew Lawler down the middle of the field with former WSU Cougar Shalom Luani picking it off. On the next he underthrew Lawler near the goal line with Breon Borders intercepting it at the 6.

“He threw the ball behind the guy down by the goal line and he chucked the other one, kind of threw it up for grabs, which is really something you don’t see us do very often so we look down upon that,” Carroll said.

Boykin also was sacked to end the half on a play that snapped with six seconds left at the Oakland 36. Carroll said the plan was to get out a quick pass to improve field goal positioning.

“Missed the opportunity at the end of the half clock-wise, too,” Carroll said. “That was a really clear situation where we knew exactly what was happening there and see if he can handle this one and that’s getting the ball out with time left on the clock and see if we can still kick the field goal and we didn’t do that well.”

Boykin said he tried to communicate to a receiver to change a route and go deeper for a possible touchdown. But that didn’t work and he said “after that there was really nothing else to do.”

Of his two interceptions he said simply “just got to make better throws.”

Boykin played well in the opener, completing 12 of 15 passes for 189 yards and a touchdown and an interception against the Chargers, a passer rating of 113.2, a performance that was portrayed at just about sewing up the backup job.

But Boykin struggled in the three games since, completing 18 of 35 passes in the next three games for 221 yards one touchdown and two interceptions a passer rating of 56.96. That included going 0 for 6 with an interception last week against the Chiefs.

Davis, meanwhile, went 10 of 16 against the Raiders for 123 yards and a 107.0 passer rating. He finished the exhibition season 24 of 35 for 316 yards, two touchdowns and no interception and a passer rating of 115.89.

“I’ve just tried to keep my head down and go to work,” said Davis, who has started 10 NFL games, eight with the Rams in 2014 including a win over the Seahawks in St. Louis. “I think I deserve to be a two somewhere whether it’s here or somewhere else.”

Now to find out if the Seahawks think similarly — it seems unlikely the team would keep three quarterbacks given logjams at other positions.

The Seahawks ended the exhibition season 4-0 for the first time since 2013, the year Seattle won its only Super Bowl.

Carroll said he thought the team had a solid preseason noting the relative absence of injuries — left tackle George Fant is the only projected starter to suffer a significant injury.

“I think we’re ready to take on the season,” he said.

That happens a week from Sunday at Green Bay, where the Seahawks have lost each of the last two seasons, an early test of two teams regarded as Super Bowl contenders.

Bob Condotta: 206-515-5699 or condotta@seattletimes.com.On Twitter @bcondotta