With apologies to the nice starts of the Pirates and Rockies, the most important story line of April has been the Braves' opening up a 3.5-game lead over the Nationals in the NL East.

Considering the importance of winning the division and avoiding the ridiculous wild-card play-in game, the last thing the Braves wanted to do was dig a hole and try to catch the Nats from behind. Atlanta's 16-9 start -- which includes a 3-2 win over Washington on Monday when No. 5 starter Julio Teheran faced off against Nationals ace Stephen Strasburg -- is even more impressive when you consider everything that has gone wrong for the Braves so far:

Six-time All-Star catcher Brian McCann hasn't played a game.

First baseman Freddie Freeman missed 14 games.

Jason Heyward is hitting .121 and is currently on the DL after an appendectomy.

B.J. Upton is .146.

Dan Uggla is hitting .177.

Teheran scuffled through 5.1 innings on Monday but allowed just two runs -- lowering his ERA to 5.08.

Justin Upton is batting .304 with 12 home runs for the first-place Braves. AP Photo/Evan Vucci

Plus, they Braves had to play 16 of their first 25 games on the road. Of course, a lot has gone right, beginning with Justin Upton hitting .304 with 12 home runs, Andrelton Simmons playing Gold Glove defense at shortstop, Evan Gattis emerging from Double-A to his six home runs, drive in 14 runs and turn into a cult hero while filling in for McCann, and the bullpen going 5-1 with a 2.07 ERA.

Most importantly, the Braves are now 4-0 against the Nationals, which means the Braves earn an A as I hand out my grades for April in the National League. Justin Upton earns an A+ for his monster month -- only four players have hit more home runs in April (Alex Rodriguez and Albert Pujols share the April record with 14) and only Bob Horner (14 in July 1980), Andruw Jones (13 in June 2005) and Ozzie Virgil (13 in May 1987) have hit more in a calendar month in Atlanta Braves history.

The Nationals, meanwhile, earn a C- for a lackluster 13-13 start -- they're 5-1 against the Marlins and 8-12 against the other major league opponents on their schedule. The Nationals also reported that Strasburg experienced forearm tightness during Monday's game and will be examined on Tuesday. Strasburg walked four while allowing just two runs in six innings against the Braves, but he hasn't been the Strasburg of 2012, or at least the Strasburg of the first three months of 2012. His strikeout rate is down, left-handed hitters have a .391 OBP against him and his ERA is 3.13, ranking just 26th in the NL. Strasburg earns a C, but teammate Bryce Harper earns an A+.

Some other NL grades for April:

Pirates bullpen: A. A key to Pittsburgh's lead in the NL Central has been a pen that has gone 6-2 with a 2.59 while pitching the second-most innings in the majors and allowing a .202 average, second behind Kansas City's .201 mark. Closer Jason Grilli has gone 10-for-10 in saves and has allowed one run in 11 innings.

Matt Harvey, Mets: A. I'd give him an A+, but he actually allowed a run against the Marlins on Monday. Harvey is 4-0 with a 1.56 ERA and has held opponents to a .153 average. He did throw 121 pitches in just 5.1 innings against the Marlins, but more than anything that serves to show that Harvey has room to get even better. Which is a scary idea if you're a National League hitter.

Marlins: D-. Last in the majors in batting average, home runs, slugging percentage, OPS and ownership.

Mat Latos and Homer Bailey, Reds: A. It seems like there's a perception that the Reds are an explosive offensive team, but that wasn't the case last year (ninth in the NL in runs scored despite playing in a hitter's park) and while the Reds are second in the NL in runs scored in 2013, they also rank ninth in slugging percentage. The Reds rotation, however, was terrific last year and has been terrific again, second to the Cardinals with a 2.97 ERA. Latos and Bailey remain two of the more underrated starters in the NL. Latos threw six shutout innings against the Cardinals on Monday, picking up his second win and lowering his ERA to 1.83. Bailey is 1-2 thanks to poor run support but has a 2.81 ERA. The two have combined for 69 strikeouts and just 17 walks, and when Johnny Cueto returns from the DL, he might give the Reds the best starting pitching trio in the league.

Cardinals bullpen: F. St. Louis starters are 14-6 with a 2.20 ERA. St. Louis relievers are 0-5 with a 5.89 ERA and .301 average allowed.

Pablo Sandoval's waistline: F.

Pablo Sandoval's bat: B.

The decision by the Brewers to sign Yuniesky Betancourt: D-. I mean, really ... Yuni was going to help the Brewers?

Yuniesky Betancourt: B+. He's hitting .286/.305/.532 and has five homers and 20 RBIs in 23 games, helping the Brewers to fight through injuries to Aramis Ramirez and Corey Hart. Don't you love baseball?

Troy Tulowitzki, Rockies: A. He's back, he's hitting, he's fielding and the Rockies are in first place. The Rockies have to hope that the strained shoulder Tulo suffered on Sunday isn’t serious (he sat Monday’s game, but there are no plans for a trip to the DL).

Matt Kemp, Dodgers: D-. Heading into Monday's games, FanGraphs rated Kemp 33rd among 36 full-time NL outfielders in WAR -- ahead of only Juan Pierre, Jon Jay and Ben Revere.

Starlin Castro, Cubs: C. I have to remind myself he's still just 23, but Castro is in his fourth season and just hasn't that much with the bat. He's hitting .271 with two home runs, but his approach -- just three walks -- is still limiting his upside. A hitter with an OBP under .300 just isn't that valuable.

Weather in Colorado: F. Please, baseball, don't play games when the weather is below freezing.