Their mathematical magic number is 10, which in most cases would mean that if they won all 10 remaining games, they'd be in, no matter what anyone else does.
Because the Dodgers and Giants play each other, and both are in play for the wild card and the NL West title, the Cubs' real magic number is eight.
If the Cubs win eight of ten, they'll be 94-68. Yes, it is possible for the Giants to finish better than that -- but if they do, they'll be West champions, and the Dodgers will be eliminated. All the other contenders have already lost more than 69 games.
Trust me on this one, and let's just focus on beating the Mets tonight.
UPDATE TO THIS: I got e-mail from John Hill reminding me that 8-2 would make the Cubs 94-68, not 93-69, and of course he's right, and I've fixed this.
Some of the permutations make my eyes glaze over, but here's one that John sent me, specific to the Giants/Dodgers series:
Dodgers 6-0, maximum of 90 Cub wins (4-6) required unless Astros go 6-3 to tie or better
Dodgers 5-1, maximum of 91 Cub wins (5-5) required unless Astros go 7-2 to tie or better
Giants 6-0, maximum of 92 Cub wins (6-4) required unless Astros go 8-1 to tie or better
Dodgers 4-2, maximum of 92 Cub wins (6-4) required unless Astros go 8-1 to tie or better
Giants 5-1, maximum of 93 Cub wins (7-3) required unless Astros go 9-0 to tie
Split 3-3, maximum of 93 Cub wins (7-3) required unless Astros go 9-0 to tie
Giants 4-2, maximum of 94 Cub wins (8-2) required
Root for it to be very one sided, preferably Dodger one-sided.
Following that? OK, if you are, read this from Ben Lauderdale, who says the key series are not the Dodgers/Giants series, but the OTHER series those two clubs play:
It is a bit misleading to say the Cubs real magic number is 8. The problem is that a magic number is really only defined with respect to a single team, so the Cubs do not really have a magic number, but the Cubs have a magic/elimination number over each of the teams that they might be in competition with:
Cubs-Dodgers: E# = 12 (i.e. if Cubs wins + Dodgers losses = 12, the Cubs will finish ahead of the Dodgers)
Cubs-Giants: E# = 10
Cubs-Astros: E# = 8
Cubs-Padres: E# = 6
Cubs-Florida: E# = 4
Cubs-Philles: E# = 4
In a normal race, the Cubs would simply need to get all of these numbers to zero, thus the largest one becomes the "magic number" and everything makes sense. But in this case, the Cubs only need to get all but either the Dodgers or the Giants to zero, since they only need to beat the worse team of those two to get the WC.
The complicated part is that since there are six games left between LA and SF, there is a guarantee that those teams can't both win out, which is not normally the case when you calculate these things. The worst case for the Cubs is for the Dodgers and Giants to finish with the same record and win all their games not played against each other, because then the Cubs have to beat both of those teams rather than just one. This corresponds to the Giants winning 4 of 6 of the head to head games and leaves both the Cubs-Giants and Cubs-Dodgers E#s at 8, thus the Cubs can guarantee a playoff berth with 8 wins and a one game playoff with 7. But 8 is not really the "magic number", because you will note that if the Cubs win six games, the Dodgers lose 4 and the Giants 2, the Cubs don't make the playoffs, but 6+2=8. In this case, the Cubs would finish one game behind a tied SF and LA, which would certainly suck a lot.
But that is a very unlikely and very dire scenario, because it assumes that the Giants and Dodgers split their series exactly 4-2 in favor of the Giants, the Dodgers sweep four games from Colorado and the Giants sweep three from San Diego. And even in this worst case, the Cubs still can clinch by going 8-2 and force a playoff by going 7-3. More realistic would be that the Dodgers take 3 of 4 from Colorado and the Giants 2 of 3 from San Diego, in which case the Cubs just need to go 7-3 to clinch and 6-4 to force a playoff. If the Giants and Dodgers instead split their series 3-3 and each lose one in their other series, the Cubs would only need to go 6-4 to clinch and 5-5 to force a playoff with the Giants. This seems to me like the most likely scenario, which is why things are looking pretty good right now. Even if the Cubs "only" went 6-4, the Astros would have to go 8-1 just to force a playoff, so we really do not need to worry about them too much at this
So, what is the upshot of all these scenarios? The really critical series are not the Dodgers-Giants series, but the Dodgers-Rockies and Giants-Padres series. If the Giants and Dodgers have bad series, the Cubs really only need play .500 ball to get into the big dance. Otherwise they will have to do a little better, but not all that much.
This is a lot to digest, so let's just figure it this way:
If the Cubs win all their games, they're in.
Let's start it tonight.
Oh, and today is the 20th anniversary of the Cubs' Eastern Division clinching game at Pittsburgh. That is the only year since 1945 that they have won more than 93 games (they went 96-65).