As for why Webb — who was 33 and playing for his third team in 1931 — had such a dramatic season is still mostly a mystery. Webb hit just 30 doubles the year before and 28 the year after. Nowlin said he knows of no spray charts that show where Webb hit his doubles.

"It was a total personal outlier," Nowlin said. "It's just sort of happened. He had hot spells and cold spells like people will. Looking at Machado, he's real close. If he should suffer an injury or get in a cold spell, it would make it more difficult. On the other hand, he could take off. You see Miguel Cabrera get the first Triple Crown since 1967 [last season]. It's not quite the same as the doubles record, but it's half a century almost."

One theory is that Fenway Park's spacious alley in right-center was a treasure trove for the left-handed hitting Webb and that he could have even settled for doubles on hits that could have been triples. After tallying six triple in 1930, Webb had just three in 1931, and he had nine in each of the next two seasons.

"He was light in '31," Nowlin said. "Maybe he would have had 64 or 63 doubles. He still had an awful lot of doubles."

"His own worst enemy"

One remarkable aspect of Machado's run is the fact that he's hit the ball all over the field. Of his 39 doubles, right-handed hitting Machado has hit 11 to the right side of the field, according to a spray chart provided by ESPN Stats and Information. Machado's highest concentration has been down the left-field line, where he's pulled 18 of his doubles.

"It speaks to just his talent level and how well he can adjust," Orioles catcher Matt Wieters said. "You just don't chase any record unless you're able to hit a lot of pitches well. He's able hit balls the other way, he's able to pull balls. For a younger player to have that kind of advanced approach to be able to use the whole field, it speaks what kind of hitter he is. In this league if you have one pitch you hit well, the pitcher is going to figure it out and pitch you a different way, but he's able to adjust to pitchers and see the pitch and hit it where it's pitched."

Machado's pace has stalled. He had 38 doubles after 83 games — and was on pace for 74 — but he's hit just one over his past 13 games.

Former major leaguer and current ESPN analyst Alex Cora said Machado's biggest obstacle might be some of those doubles turning into home runs.

"In some ways, he might end up being his own worst enemy," Cora said. "As the season goes on, a lot of those balls might start becoming home runs. It's getting warmer and that stadium is a good place for homers."

Machado agrees that he still has room to grow, and he hopes his doubles stroke will translate into more homers as he matures.

"With more experience at the plate, you're going to be a smarter hitter," he said. "Definitely with more experience, hopefully they do turn into home runs. I haven't gotten my man strength yet. Eventually that will come. And when that time comes, hopefully they will go out. Hopefully they will. In the meantime, I'll just keep hitting doubles and getting on base."

Markakis, another hitter who was expected produce more power because of his early-career doubles numbers, said the stats alone aren't a true indicator.

"It's hard to tell," Markakis said. "Some guys fill out. A lot of people say guys will fill out. These days you don't know what the heck to expect with what everyone is doing these days. I lot of people mature differently. If he fills out like everybody says and thinks he's going to do, yeah, I think he's going to start turning some of those doubles into home runs."

Markakis also said that with Machado's smooth swing producing its share of line drives — 24 of his doubles have come on line drives — there should be patience in waiting for him to develop power.

"The other thing you've got to look at is he's not a guy who goes out there and flies out to the warning track," Markakis said. "He's a guy who drives the ball and hits line drives and works gap to gap, hits them down the lines and works the whole field. Power is the last thing that's going to come. I think the thing that impresses me the most is his swing and his approach at the plate. If I was the manager, I'd take that every day and if the power didn't come, then that's fine."

Showalter is indeed fine with that.

"Here's the deal," the manager said. "I don't think that he's going to hit this many home runs or this ball's going to carry. Manny is a line drive guy, and I just think he's going to be as good as he's capable of being. That's the only thing I want to know. … I'm confident when I go to bed at night that he's going to be as good as he's capable of being. That's the only thing I ask. What he will be, nobody knows. His home run totals could go down. I don't know. I'm OK with it. But he's going to reach his potential, as long as we don't screw him up."


Most doubles at the All-Star break

A look at hitters who had the most doubles at the All-Star break in major league history. Machado has played more games than the rest of the field, but he is still on pace for 66 doubles, which would be one shy of the single-season record

Name     Team     Year     Doubles at break     Games at break     Season total
Edgar Martinez     Sea.     1996     42     85     52
Manny Machado     O’s     2013     39     96     ??
Craig Biggio     Hou.     1999     38     87     56
Chuck Knoblauch     Minn.     1994     37     83     45
John Olerud     Tor.     1993     37     87     54
Lyle Overbay     Mil.     2004     37     86     53
George Burns     Cle.     1926     36     78     64
Paul Waner     Pit.     1932     36     72     62
Earl Webb     Bos. (AL)    1931     36     73     67

Most doubles in a single season

Name     Team     Year     Doubles
Earl Webb     Bos. (AL)    1931     67
Joe Medwick     St.L. (NL)    . 1936     64
George Burns     Cle.     1926     64
Hank Greenberg     Det.     1934     63
Paul Waner     Pit.     1932     62
Charlie Gehringer     Det.     1936     60
Todd Helton     Col.     2000     59
Chuck Klein     Phi. (NL)     1930     59
Tris Speaker     Cle.     1923     59
Carlos Delgado     Tor.     2000     57
Billy Herman     Chi (NL)     1936     57
Billy Herman     Chi (NL)     1935     57
Brian Roberts     O’s     2009     56
Garret Anderson     LAA     2002     56
Nomar Garciaparra     Bos.     2002     56
Craig Biggio     Hou.     1999     56
George Kell     Det.     1950     56
Joe Medwick     Stl. (NL)     1937     56
Lance Berkman     Hou.     2001     55
Gee Walker     Det.     1936     55