By Chris Emma–

CHICAGO (CBS) — For all the wrongs of Bud Selig’s tumultuous tenure as commissioner of baseball, he certainly was right by adding a second wild-card.

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Drama permeates through the pennant push. Teams are less likely to sell, for better or worse — ahem, White Sox — because the additional playoff spot offers a glimmer of hope.

The Cubs own the fourth-best record in baseball, a 72-51 mark entering Tuesday’s night contest against the Giants, but it’s only good for third in the NL Central. Fortunately for Chicago, its North Side club currently occupies the second wild-card spot, which seems to be destined for a date with Pittsburgh.

With Chicago’s lead over trailing San Francisco mounting — a 6.5-game advantage entering this three-game series out West — it’s fair to look ahead to that one-night stand, likely with Pittsburgh. With that in mind, one question continues to loom: Should the Cubs start Jon Lester or Jake Arrieta? This is a good quandary to have, and the Cubs should have their choice, given their big lead.

Despite a few rough patches, Lester has largely looked well worth the $155 million appointed ace for the Cubs’ wide-open window of contention. Lester boasts a 3.11 xFIP, ranking 13th in the majors and placing just behind Gerrit Cole, the Pirates’ likely starter for a wild-card game. Lester has a 3.3 WAR, a mark good for eighth in the National League.

“I’m a perfectionist,” Lester said in May. “I want to be perfect all the time.”

Throughout most of the season, Maddon has given his strongest backing of Lester’s work. He trusts the dependability of a veteran who has won a World Series, and he also respects the ability to bounce back from a rough outing.

Overall, Lester has been impressive at the top end of the Cubs’ rotation, sporting a 3.44 ERA.

“Every starter’s going to have a hiccup now and then,” Maddon said. “They all are — it’s impossible to not. But for the most part, (Lester’s) been nails.”

Of course, Arrieta hasn’t endured many — if any — hiccups during a season that will earn him Cy Young notice. He ranks ninth in baseball with a 4.6 WAR, is sixth with a 2.84 xFIP and seems to be getting better each start. He checks in at 15-6 with a 2.30 ERA.

Arrieta has surrendered zero or one run in 13 of his 25 starts. The most earn runs he’s allowed in a start were four, which he hasn’t done since June 16. And since that point, he has a 1.26 ERA and 2.23 FIP, allowing 12 earned runs in 86 innings. While the wins stat is largely worthless, it’s worth noting the Cubs are 9-1 in that run, symbolizing his ability to give the team a chance to win.

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So, should he get the ball for a potential play-in game?

“Everybody wants to pitch in the postseason,” Arrieta said of the topic last Thursday. “I think still, at this point in time, we don’t intend to be a wild card. We still think we can win our division.”

It all makes fun conversation, something kept especially comfortable with a sizable lead over San Francisco.

But what the Lester-Arrieta debate illustrates is the solid position that the Cubs occupy. Lester was paid mega money to anchor the rotation as an ace, and the emergence of Arrieta as one of baseball’s best pitchers comes as a pleasant surprise. Arrieta has dedicated himself to a specific diet and routine, one which he credits for the success.

In a way, Arrieta’s pure dominance has seemingly cast an unfair shadow of Lester, who has been good — just not great like his teammate. Fans expect more of Lester, as heard loudly with boos after Detroit roughed him up last week.

“What happened against Detroit?” Lester responded slyly to a question after Monday’s stellar outing of 8 2/3 innings and one earned run allowed in a win against the Indians.

The 31-year-old Lester was brought to Chicago knowing his best years would be at the front of the seven-year contract, and some struggles could come toward the end. If the Cubs win a World Series during that time, who really cares?

Regardless, the Cubs have two top-end starters who have proved to be among the game’s best. One is meeting expectations, the other is far exceeding them. Neither have shown any signs of slowing down.

Important decisions loom for Maddon, with none potentially greater than picking a starter for the potential wild-card showdown. Who is the best option on the bump, Lester or Arrieta?

The Cubs can’t go wrong with either.

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Follow Chris on Twitter @CEmma670.