There is something "extra" special about the season the Red Sox are putting together.Yes, Boston is 88-64 and holds a three-game lead over the Yankees atop the American League East. But it's how the club has scratched its way to so many of those victories that makes it stand out

There is something "extra" special about the season the Red Sox are putting together.

Yes, Boston is 88-64 and holds a three-game lead over the Yankees atop the American League East. But it's how the club has scratched its way to so many of those victories that makes it stand out from the crowd.

Prior to Wednesday night's 9-0 win over the Orioles, the Red Sox had won both of the series' first two games in 11 innings -- 10-8 on Monday and 1-0 on Tuesday. That gave them four extra-inning wins since Sept. 5, moving their 2017 record in extras to a mind-boggling 15-3 (.833).

As it stands, Boston would be just the fifth club since at least 1913 -- and second since '60 -- to win at least 15 extra-inning games in a season with a win percentage that high. That is some select company.

Extra innings: 15+ wins and .833+ win%

1949 Indians: 18-1 (.947)

1959 Pirates: 19-2 (.905)

2012 Orioles: 16-2 (.889)

2017 Red Sox: 15-3 (.833)

1927 Cubs: 15-3 (.833).

Here are some other facts and figures to know about Boston's incredible success beyond the ninth inning:

• The Orioles (12-7, despite the two losses this week) and Giants (12-7) are the only other teams to even reach double digits in extra-inning victories this season. The only teams with fewer extra-inning losses (Indians and Cubs) have played just six games apiece, going 4-2.

• Dating to 1913, Boston is just the 27th team to win at least 15 extra-inning games in a season, regardless of record. The only others to do it since MLB expanded to 30 teams in 1998 are the 2013 D-backs (17-8), '12 Orioles (16-2), '05 Twins (15-8), '03 Reds (15-5) and 1999 Braves (17-5).

• One more victory would make the Red Sox only the 14th team since at least 1913 to get to 16 extra-inning wins in a season. Just five clubs in that time have reached 17, with the 1959 Pirates the only club at 19.

• The only other time the Red Sox have captured at least 15 victories in extras was in 1943, when they went a mere 15-14 while struggling to a 71-81 overall record. Boston won a total of 14 games in extras from 2015-16 and as recently as '12 won only two (while losing 10).

• It's not as if the Red Sox are only playing games of 10 or 11 innings. They've gone at least 12 on eight occasions and at least 15 on four occasions, with a long of 19 in a 3-2 win over the Blue Jays on Sept. 5. Those four contests of 15-plus frames (3-1 record) are tied for the most in a season in Sox history with the 1951 club (also 3-1). They also account for nearly half of the nine total MLB games this season to go at least 15.

• Red Sox pitchers have combined to allow eight earned runs in 57 2/3 extra innings, for a 1.25 ERA. They have allowed a .185/.258/.231 line, with 55 strikeouts and just five extra-base hits. Despite facing the most batters in extra innings of any team, Boston's .489 OPS allowed trails only the Cubs (.421), who have played just six extra-inning games.

• Righty Richard Hembree has three more extra-innings appearances than any other member of the staff. In 7 2/3 frames, he has allowed just one run on five hits, struck out seven and posted an opponent OPS of .563.

• Sox batters have put together a .274/.379/.361 line in extras, with a .740 OPS that is right in line with the team's overall mark. Thanks in large part to the volume of chances, Boston does lead MLB with 60 hits, 10 doubles, 32 walks and 32 runs scored in extras. The team total of reaching base safely 97 times in extras trails only the 2013 D-backs (116) over the past 20 seasons.

• The extra-inning stars on offense have been Mookie Betts (1.004 OPS, four RBIs), Sandy Leon (1.357 OPS, four RBIs) and Andrew Benintendi (.779 OPS, seven RBIs), who is tied for the MLB lead in hits (nine) and RBIs in extra frames. Hanley Ramirez also has provided two walk-off hits in the 15th or later, a 19th-inning single on Sept. 5 and a 15th-inning homer on July 18.

Andrew Simon is a research analyst for MLB.com. Follow him on Twitter @AndrewSimonMLB.