As the 2013 baseball season rounded the Memorial Day corner and entered the month of June—the traditional milestone at which it becomes appropriate to stop considering the season to be in its early stages, as the summer campaign begins—the aggregate record of the five teams comprising the National League West Division stood exactly at .500, with 135 wins and 135 defeats. In other words, the division was performing at the very definition of league-average.

However, June was a cruel month for the NL West. It slumped to 65-73 for those 30 days, a .471 percentage that wasn’t just below league-average, it was in fact the very worst in the majors. And as June has given way to July, instead of snapping out of it, the division has swooned further still. Through Saturday’s games, the July NL West was sputtering to the tune of 9-18.

A peculiar feature of this dispiriting performance is that the team in the division that was doing the very worst through May—the cellar-dwelling Los Angeles Dodgers, with manager Don Mattingly’s firing assumed all but a done deal—has turned around and played the division’s best ball. Indeed, the Dodgers have achieved the NL West’s only winning record since the first of June.

Just what the heck is going on here?

A Dodger blue revival

Mattingly’s job has been saved, and the Dodger season transformed, by the arrival of a 22-year-old outfielder from Cienfuegos, Cuba, by the name of Yasiel Puig. Signed to a seven-year deal just a little over a year ago, he then obliterated opposing pitchers in 63 minor league games, and on June 3, Puig commenced punishing major league hurlers.

In his first big-league week, Puig hit .464 with four homers, and at the 30-game mark he was still at .420/.449/.706. In addition to scorching power, Puig has demonstrated a cannon (if wild) arm and outstanding speed. If he isn’t yet baseball’s biggest 2013 story, Puig is working on it ardently.

To be sure, L.A.’s mood also has been brightened by the early-June return from the disabled list of shortstop Hanley Ramirez, who’s also hit over .400 with terrific power.

With strong years already being delivered by the key high-priced veterans acquired last August in the massive trade with Boston (first baseman Adrian Gonzalez and left fielder Carl Crawford) , the Dodgers suddenly possess a serious offensive core. This is true even though neither of their erstwhile hitting stars—center fielder Matt Kemp and right fielder Andre Ethier—have been able to get hot.

This Dodgers team still has holes, particularly at the back end of the starting rotation and in the bullpen, where Brandon League, brought in as the $7.5 million-per-year closer, has been terrible. But with the ever-brilliant Clayton Kershaw as well as impressive Korean import Hyun-Jin Ryu each taking the mound every fifth day, and now recent acquisition Ricky Nolasco as well, the Dodgers are newly formidable.

The ball club that was effectively pronounced dead in the spring has come quite alive this summer, and could well find itself with a heart beat into October.

Not very deadly Diamondbacks

In early July, first place remains the possession of the Arizona Diamondbacks, as it has since mid-May. But this has been far less a function of strong play by the Snakes than it has been their lack of divisional competition. On the June 7, Arizona held a 2.5-game lead. They then proceeded to lose 15 of their next 23 games, yet they still held a 2.5-game lead.

The D-backs have been led by two breakout stars, 25-year-old first baseman Paul Goldschmidt and 23-year-old starting pitcher Patrick Corbin. Goldschmidt, in his second full big league year, is leading the league in RBIs and is in the league’s top five in doubles, home runs, total bases, slugging, and OPS. Corbin, in his first full season, is in the top ten in wins, innings, and ERA, and through Saturday, the Diamondbacks were 15-2 in his starts.

But the list of Valley of the Sun frustrations has been long. Second baseman Aaron Hill, a Silver Slugger award winner in 2012, missed more than two months with a broken hand. Third baseman Martin Prado, the key acquisition in Arizona’s controversial offseason trade of Justin Upton, hasn’t hit well, and neither has former All-Star catcher Miguel Montero.

Left fielder Jason Kubel belted 30 home runs in 2012; so far this year he has four. Starters Wade Miley, Ian Kennedy, and Trevor Cahill won 16, 15, and 13 games, respectively in 2012; more than halfway through this year, they’ve won five, three, and three.

Cracks in the Rockies

Through the early weeks of 2013, the pleasant surprise NL West team was the Colorado Rockies. Dead last at 64-98 in 2012, this season’s mile-highers were in first place into early May and tied for the top spot for a few days late that month. They haven’t managed to win as many as three games in a row since then.

The key blow that sent these Rockies tumbling was the broken rib that put superstar shortstop Troy Tulowitzki on the DL in mid-June. Outfielders Carlos Gonzalez, Dexter Fowler, and Michael Cuddyer have all hit well, but in Tulo’s absence, the Colorado offense begins and ends with those three.

A Hardball Times Update by Rachael McDaniel Goodbye for now.

And while the Rockies’ pitching remains distinctly improved from 2012 overall, the trend line there is not encouraging. The team earned run average was 3.75 in April, 4.02 in May, 4.75 in June, and—through Saturday—7.95 in July.

Pitching-poor Padres

Speaking of mound trouble, only one National League team (and we’ll get to it) has a worse team ERA+ than the San Diego Padres so far in 2013.

Management moved Petco Park fences closer to home plate this season in an effort to relieve the frustration of Padres’ hitters. Well, okay. Despite the persistence of cool sea-level, ocean-breezed air (which is beyond the control of Padres’ management), the Padres’ bats have achieved middle-of-the-pack accumulation of home runs and runs scored.

But San Diego pitchers, not a good staff to begin with, are less than delighted. In 2012, five of the 16 National League teams surrendered more big flies than the Padres, but in 2013, just one of 15 teams has coughed up more long balls than San Diego.

The rebuilding Padres are developing an interesting, and potentially quite good, young keystone combination. Twenty-six-year-old shortstop Everth Cabrera (a Rule 5 draft pick half-a-decade ago), already a base-stealing champion, is hitting for average for the first time, and he’s been a force at the top of the San Diego order.

Twenty-four-year-old rookie second baseman Jedd Gyorko is a very different sort of talent. Stocky, slow afoot, and power-hitting, he was excellent until going down with a groin pull in mid-June. He’s due back following the All-Star break.

Free falling in San Francisco

The defending World Series champs weren’t doing great in late May, but they certainly weren’t doing badly: 28-22 as of May 26, tied for first place. Since then everything has gone horribly: 12-24 through Saturday’s games, the very worst in major league baseball.

A face-plant of this scale clearly has many causes. The Giants had scored 243 runs through the end of May, or 4.5 per game. Since then they’ve scored 99 runs, or 3.1 per game. Shortstop Brandon Crawford entered June hitting .283/.349/.449 with 25 RBIs; since then, he’s hit .212/.262/.232 with three RBIs. Right fielder Hunter Pence since mid-June has gone 11-for-69, and third baseman Pablo Sandoval, since returning from the DL on June 24, has hit .122/.163/.146.

But perhaps even more distressing than the Giants’ recent offensive slump has been the season-long weak performance of their pitching.

This staff, and in particular the starting rotation, was the foundation of San Francisco’s 2010 and 2012 championships, but this year only Madison Bumgarner has been an effective starter. Working in an environment in which the league-average ERA is 3.43, through Saturday Barry Zito was 4-6 with a 4.44 ERA, Tim Lincecum was 4-9, 4.66, and worst of all, Matt Cain was 5-5, 4.85, with 16 home runs allowed.