DYK? MLB's HR record eclipsed in '17

Baseball's single-season record for total home runs was rewritten Tuesday.
Tigers outfielder Alex Presley's fifth-inning homer off Daniel Gossett of the A's tied the Major League record for total home runs at 5,693, originally set during the 2000 season, and Royals left fielder Alex Gordon's eighth-inning dinger off Blue Jays right-hander Ryan Tepera soon after set the new standard -- with 12 days remaining in the regular season.
"I came into the clubhouse after [Darwin] Barney hit the home run, and I heard them talking about it. So I was kind of aware that we were getting close to it," Gordon said. "Then after I walked back to the dugout, I kind of forgot about it. I hit the home run and [they] told me when I got back in the dugout. A pretty cool thing to be a part of.
"I didn't hit many this year, but I guess I made one count."

Thanks to the overwhelming contributions from Giancarlo Stanton to Aaron Judge to Scooter Gennett -- and everyone in between -- the 2017 season seemed destined to eclipse the home run record almost from the very beginning. Baseball has become more homer-happy than ever, but how did we get here? Below are some things you should know about "The Year of the Home Run" (stats through Monday's games).
• The record-tying and record-breaking home runs came from some unlikely sources. Presley's homer was just his second of the season, while Gordon cleared the fence for the eighth time.
• We've already seen players record 374 multi-homer games this season, clear of the previous single-season record of 362 set in 1999. This included a record run of 28 consecutive days from May 30 to June 26 in which at least one player enjoyed a multi-homer game, according to the Elias Sports Bureau. A total of 337 multi-homer games were recorded by players last year.

• Yasmani Grandal and Ian Kinsler became the 109th and 110th players to reach at least 20 home runs Tuesday, putting 2017 right on the doorstep of featuring the most 20-homer hitters of any season in history. Last year saw 111 players reach the 20-dinger mark, and the previous high had been 103 back in 1999.
This year's 20-homer club features plenty of first-timers -- 38 to be exact -- which trails only 2016 (41) for the most first-time 20-homer hitters in a season.
• The glut of the "middle class" of homer hitters is found at the 10-homer club, which already contains a record 231 players. For context, that's more than half of the 430 Major Leaguers who have recorded at least 100 plate appearances.
Interestingly, 153 batters have recorded at least 15 homers in 2017, while 149 have totaled enough plate appearances to qualify for the two leagues' batting titles.

• When the weather heated up, so too did Major League sluggers. The top two calendar months in Major League history in terms of home runs were recorded this season with August (1,119) edging out June (1,101) atop the all-time list. MLB hitters also combined to club 1,060 homers in May, meaning three of the top-five homer months in history took place this year.
• This year's home run surge has seen teams depend on the long ball for offense more than ever. As of Monday, the 30 Major League clubs had combined to score 42.4 percent of their total runs via homers. That would break the all-time mark of 40.2 percent of runs via home runs set last year, according to Elias.
A look at individual teams reveals we're on the doorstep of additional history. According to Elias, both the Blue Jays (50.5 percent) and Athletics (48.8 percent) are on pace to record the fourth- and fifth-highest rates of runs scored via home runs in a season. Only the 2010 Blue Jays (53.1 percent), and the 2016 Orioles (51.9 percent) and Mets (51.1 percent) relied on the long ball more.
Dating back to 1913, 164 individual teams have recorded a 200-homer season in the more than 100 seasons of Major League Baseball on record. Thirteen of those teams, or roughly 7.9 percent, have come from this season alone. The Royals have already passed their single-season franchise record for homers, while 14 other clubs were within 30 dingers of their own franchise marks entering Tuesday.

• The game's power surge has undoubtedly been aided by the wave of young players entering with a better understanding of optimal slugging approaches at the plate. We've already seen nine players with rookie status club 20 or more homers, surpassing the record of six set both last year and in 2006. We may see more by season's end, considering Andrew Benintendi is sitting on 19 home runs and Yuli Gurriel has 17. The rookie club is led by Judge (44 homers) and Cody Bellinger (38, tied for the NL rookie record), who are the first pair of rookies to each homer at least 35 times in the same season.
Rhys Hoskins can't be left out of this conversation, considering he's the fastest player in history to hit 18 home runs when he got there in just his 34th career game. And Oakland's Matt Olson has come on strong over the second half, becoming the first player since Giancarlo Stanton in 2010 to club 20 homers in both the Minor and Major Leagues within the same season.
• Not all of this year's homers have cleared the fences. In fact, Chris Taylor's leadoff inside-the-park home run for the Dodgers on Monday night was the 18th hit across MLB this year, which is the most since 2010. That included eight non-fence-clearing homers hit in August alone, which was the most recorded in any calendar month since May 1997. The only season this century that featured more inside-the parkers was 2000 with 20.

• There have been many discussions about how baseball's "fly-ball" revolution (or "air-ball revolution", depending on your preference) has contributed to the homer surge, and Statcast™ technology helps us quantify that change. As a unit, MLB hitters have steadily raised the rate in which they've lofted balls with "ideal" launch angles between 15 and 40 degrees (i.e. the range that accounts for nearly all the home runs hit this year) and their rate of barrels (or balls hit with ideal combinations of exit velocity and launch angle that most often turn into extra-base hits) hit per batted ball. They're also homering more against elite pitch velocities as more and more hard-throwing hurlers enter the big leagues:
MLB hitters' "ideal" air-ball rates / barrel-per-batted ball rates / home-run rate per batted balls off 95-plus mph pitches
2015: 29.4 percent / 5.3 percent / 3.4 percent
2016: 30.1 percent / 6.2 percent / 3.6 percent
2017: 30.6 percent / 6.3 percent / 4.2 percent