The Arizona Diamondbacks may be on pace to win their second straight National League West crown — but they may also be headed for a less glorious achievement. Since divisional play began in 1969, there have been two teams who held first place with a sub-.500 record this late into the season, and the 47-48 Diamondbacks are half of that unfortunate pair.

History might excuse the only other team to match this dubious achievement. The 1994 season for the Texas Rangers was ended by that year’s work stoppage. The Rangers were in first place in the American League West with a record of 52-62 — and they were a less humiliating 44-46 as of July 16 — theoretically allowing for the possibility that they could have finished the year above .500 and as division champions if not for the strike.

There have been some close calls in the past this late in the year, however. The 1974 Phillies were 46-44 on July 16, and though they finished under .500 at 80-82, they had fallen to third place by that point. The Phillies had another close encounter on July 16, when they were 43-41 in 1983. This club improved dramatically from that point, however, finishing first in the NL East with a 90-72 record in a season that saw them fire manager Pat Corrales on July 17 and replace him with Paul Owens. The team turned things around under their new manager, thanks in no small part to the excellent second halves of Mike Schmidt (.272 AVG/.420 OBA/.576 SLG) and Joe Lefebvre (.305/.384/.507).

Most of the other close calls have come since Major League Baseball switched to its current six-division format. The 1994 Los Angeles Dodgers weren’t that much better than the Rangers in leading the NL West with a 47-44 record. The 1997 Pirates were another weak contender with a 47-46 showing, but they finished in second in the NL Central with a 79-83 record. Most recently, the world champion 2006 St. Louis Cardinals had the opposite problem: They were 52-39 as of July 16 and in first place in the NL Central, but barely managed to slip into the playoffs with an 83-79 record.

Where do this year’s Diamondbacks club fit into this picture? Although currently one game under .500, you have to remember that this is a team that, on April 30, was sporting a shiny 20-8 record. Since then, they have gone just 27-40, and if they were in any other division, would have long since relinquished their divisional lead. This is the NL West, though.

To run through the division’s weak field and each team’s issues, the Diamondbacks have hit .240/.314/.380 since May 1, well below the National League average of .258/.329/.409, and a serious issue given that their pitching has been suspect for just as long. The pitchers have given up a worse line than what the lineup has produced: When you allow the opposition to hit .260/.322/.408 and your lineup cannot best that level of production, you’re going to lose more often than not. Let’s not forget the above line for the offense is their total effort. Break the numbers into home (.265/.336/.416) and road (.218/.293/.347) splits, and Arizona’s 11-24 record on the road since May 1 makes that much more sense.

The bullpen isn’t good enough for the Diamondbacks to do much better than .500 in extra-inning or one-run games, as they rank 21st in Win Expectation Above Replacement (WXRL). There are a handful of individual relievers around the game who have generated more value above replacement than the entire Diamondbacks bullpen. The rotation is nowhere near as awful as the pen — they are ranked 11th in Support Neutral Lineup-Adjusted Value Added Above Replacement (SNLVAR) — but that is mostly due to the work of Dan Haren and Brandon Webb, the club’s co-aces. Webb would be performing at an even higher level if not for a terrible infield defense; the Snakes’ infield has four players who all rank near the bottom of their respective position in defensive value, which has certainly contributed to some of the struggles of other Arizona pitchers as well.

Given the way they’ve played outside of April, it would be no surprise if the D’backs fell off the pace much like the 1974 Phillies or ’97 Pirates. For those who hope to see a team win a division with a sub-.500 record, though, the second-place Dodgers may be no better off than Arizona. Although only one game back with a 46-49 record, they’re in an equally bad spot in more ways than that.

The Dodgers are just as poor of an offensive team as the Diamondbacks, with a .249 team EqA. With Rafael Furcal (one of their best hitters in the early going) out for the season, it’s likely they may not receive any further production out of shortstop and will play just as poorly down the stretch as they have all year, unless the always fragile Nomar Garciaparra can discover the fountain of youth or bathe in the River Styx to gain invincibility from injuries.

Their starting pitching is on par with the D’backs, if not a little better, and their bullpen is inarguably superior. They rank fifth in the majors in WXRL, with nearly double the value of the D’backs pen, and while losing Takashi Saito until possibly September may bring them back to the pack, the bullpen’s a strong enough unit to survive that in the short term.

That combination promises a better club than the Diamondbacks from here on out, one that might take the division lead as soon as this weekend. But the Dodgers are still under .500 for a reason — that below-average offense — and with the bullpen temporarily weakened, there’s reason to believe they may very well finish the year bobbing around .500, even with the division lead (assuming Arizona does likewise).

Regardless, the race out West is hypnotic, though not for the reasons we would normally find a race compelling. Instead, we see two teams flailing atop the division for no other reason than someone has to win. It’s never happened in baseball before, but there’s a first time for everything.

Mr. Normandin is a writer for Baseball Prospectus. For more state-of-the-art commentary, visit baseballprospectus.com.