On July 28, the Chicago Cubs lost 7-2 to the Rockies as starter Dallas Beeler got knocked out in the second inning. The Cubs were 52-47. All things considered, it had been a successful season up to that point, as the young Cubbies were just 2.5 games behind the Giants for the second wild card.

Since then the Cubs have gone 20-4, the best record in the majors, and they entered Monday leading the Giants by six games for the second wild card. The Cubs have even reached out to season-ticket holders about purchasing playoff tickets.

Let's see what has sparked this hot streak (stats don't include Monday's walk-off win):

1. Offense

Through July 28, the Cubs were hitting .237 AVG/.314 OBP/.371 SLG and averaging 3.84 runs per game, ranking 10th in the NL in runs per game. Since then, they've hit .267/.347/.494 rank first in the NL in runs per game at 5.61. Rookie Kyle Schwarber has received a lot of attention during this stretch, and with good reason. He's hit .238/.354/.563 with eight home runs, 23 runs and 21 RBIs in the 22 games he's played, but he hasn't been the best Cubs hitter during the team's hot streak:

Anthony Rizzo -- .341/.433/.732, 9 HRs, 25 RBIs

Dexter Fowler -- .315/.436/.629, 5 HRs, 21 runs

Kris Bryant -- .308/.409/.560, 5 HRs, 15 RBIs

Besides those three, Addison Russell has hit .305 while slugging .500; Miguel Montero has hit .289/.400/.632 in 12 games since returning from the DL; Chris Coghlan has hit four home runs; and Jorge Soler has hit .280 with 14 RBIs. It's been a team effort.

2. Pitching

Through July 28, the Cubs had a 3.51 ERA and ranked sixth in the NL with 3.87 runs allowed per game. Since then: 3.64 ERA and 3.78 runs allowed per game. While that ranks third in the league in that span, this hot streak has been sparked by the offense, not the pitching. Jake Arrieta is worth noting, however; he was good up to July 28 but has been nearly unhittable in five starts since, going 4-0 with a 1.08 ERA and .169 batting average allowed. The late-inning relief also has been stellar, as Hector Rondon, Pedro Strop, Justin Grimm and Tommy Hunter have combined to allow just nine runs in 42 1/3 innings.

3. Defense

The big risk from manager Joe Maddon came on Aug. 7, when Montero returned. Schwarber had been filling in at catcher but moved to left field, a position he hadn't played all season in the minors. Left fielder Coghlan shifted to second base; while he had played there in the minors, he'd played only 7 2/3 innings there in his major league career. Second baseman Russell was moved back to his natural position of shortstop, with Starlin Castro going to the bench. Maddon likely was downgrading defensively at two positions while entrusting shortstop to a rookie. The Cubs have gone 12-3 since the lineup maneuverings.

The benefit here, however, is that the early returns suggest Russell will be a big defensive upgrade over Castro. He is already rated at plus-2 defensive runs saved compared to Castro's minus-6, helping offset the drop from Russell to Coghlan/Castro at second base. Schwarber is obviously in the lineup for his bat, but Coghlan was only average at best in left field, so while it's a drop-off in range, it's not like the Cubs had a Gold Glover in left to begin with.

The other interesting note about the Cubs' defense is that Maddon hasn't shifted nearly as much as he did with Tampa Bay. The Rays were second in the majors in shifts in 2014 under Maddon, but the Cubs rank 24th in the majors in shifts this season, on pace for about 450 fewer shifts than the Rays had in 2014. National League teams in general shift far less than AL teams, so it may be a reflection of that, but it also may be a sign that the Cubs' front office doesn't hold shifting in the same regard as Tampa Bay's front office.

4. Luck/timing

No surprise, this stretch has come largely against some bad teams: Yes, there were six games against the Giants (who the Cubs swept) and Pirates, but seven against the Brewers (without Carlos Gomez), four against the Braves, two against the David Price/Yoenis Cespedes-less Tigers and three against the White Sox. Against the Pirates, the Cubs faced J.A. Happ and Jeff Locke instead of Gerrit Cole and Francisco Liriano. Chicago missed Madison Bumgarner in the Giants series. The loss against the White Sox did come against Chris Sale.

Anyway, after Monday's makeup against Cleveland, the schedule gets a little tougher, starting Tuesday with a big road trip to San Francisco and Los Angeles. The Cubs can almost put the San Fran away in the wild-card race with a sweep or even by taking two out of three. They still have two series left with the wild-card leading Pirates and two with the Cardinals, who lead the Central.

Overall, the Cubs' playoff odds look strong -- 95 percent, according to FanGraphs. They may not get a playoff game at Wrigley since they could end up playing the wild-card game in Pittsburgh or St. Louis, but maybe Cubs season-ticket holders should go ahead and order those playoff tickets. The impending Cubs' dynasty apparently has arrived a year early.