Mercury vs. Sky? How'd that happen?

BG versus Big Syl. The UConn legend versus the Husky-who-might-have-been. The heavy favorites versus the refuse-to-succumb underdogs. The Valley of the Sun versus the Windy City.

That's the WNBA Finals matchup: West winner Phoenix, led by Brittney Griner and Diana Taurasi, versus East winner Chicago, led by Sylvia Fowles and Elena Delle Donne.

And if you picked those two teams to meet for the league title … well, you're definitely not me. Because I had put my two cents (and not a penny more) on a repeat of the 2012 WNBA Finals matchup of Minnesota and Indiana. For that matter, my preseason predictions had Chicago finishing last in the East.

The thing is, for a significant part of this summer, that didn't seem wrong. The Sky really did struggle with injuries and illness, as the team that led the East in victories in 2013 had to piece things together day to day much of this year.

However, here we are with the last two teams standing, and one is a surprise to nobody: The Mercury had a league-record 29 victories. The Sky, by contrast, won almost as many games in the past two weeks (four) as they did during the entire two months of June and July (six).

Phoenix is one of the WNBA's original franchises (the league began in 1997) and is in its fourth WNBA Finals, having won two titles. The Sky are an expansion team that began in 2006 and didn't win a playoff game until this August.

It's the first time since 2008 that the East representative in the WNBA Finals isn't Atlanta or Indiana. Those are the teams the Sky beat to get this far, both in a deciding Game 3 on the road. Each of those wins was stunning.

Chicago on paper projected to match up better with Atlanta, so the fact that the Sky won that series wasn't actually a huge shock. Rather, it was how the Sky did it: appearing completely out of Game 3 -- down 17 with 8 minutes left -- until a riveting comeback led by Delle Donne.

Then the series against Indiana seemed a more difficult matchup for the Sky, and they had to go double overtime to stay alive with a Game 2 win.

With the deciding game being held in Indianapolis, the Fever playing to extend coach Lin Dunn's career and Delle Donne slowed by a balky back, the Sky appeared to be at the dollar store with 90 cents in their pocket. But it turned out to be the Fever who came up short.

The Sky threw a blanket on the Indiana offense. And despite getting just four points from Delle Donne, Chicago had more than enough scoring punch to move on, winning 75-62 Wednesday. But will the Sky finally run out of answers against the might of the Mercury?

That's what you'd expect … but then again, based on a lot of expectations, the Sky's season was supposed to be over a couple of weeks ago. At this point, the Mercury are not going to make the mistake of being overconfident. That Phoenix has the upper hand, though, is undeniable.

The Mercury won both regular-season meetings with Chicago: 87-69 on July 2 in Phoenix, and 72-66 on July 11 in Chicago. Delle Donne didn't play in either of those games; she missed most of June and July dealing with the effects of a flare-up of Lyme disease.

Her back problems limited her against Indiana; she played just more than 20 minutes in Game 3. If she can make progress healthwise by Sunday's Game 1 (ABC, 3:30 p.m. ET), she's clearly one of the marquee players in the WNBA Finals.

Delle Donne, of course, is the UConn recruit who never actually played for the Huskies. After a very brief time in Storrs the summer before her freshman year was to start, she went home to Delaware. After one volleyball season and four tremendous basketball seasons for the Blue Hens, Delle Donne was drafted by the Sky at No. 2 behind Baylor's Griner last year.

Delle Donne won WNBA Rookie of the Year honors, but Griner also has been a success with Phoenix. Part of the so-called "Three to See" from the college senior class of 2013 along with Notre Dame's Skylar Diggins, Griner and Delle Donne are meeting with a championship on the line in just their second season in the WNBA. (And Diggins, incidentally, won the league's Most Improved Player award this year for Tulsa.)

From a name-recognition and marketing aspect, the league probably couldn't be happier to have Griner and Delle Donne in the WNBA Finals spotlight. And it will be interesting to see how they perform.

Other than an off game in the Mercury's playoff opener against Los Angeles, 6-foot-8 Griner has been pretty much unstoppable when she has the ball so far this postseason. In her past four games, Griner has made 33 of 43 shots from the field (76.6 percent) and 14 of 14 free throws.

But now she'll be going against another true center who has the size, talent and experience to potentially slow Griner. Fowles, who is 6-6, was the No. 2 draft pick in 2008, and Big Syl has averaged 15.7 points and 9.8 rebounds in the regular season over her seven-year career in Chicago.

This series also has its so-called unsung heroes on both teams. Phoenix's Candice Dupree and DeWanna Bonner are critical parts of the Mercury's attack, on offense and on defense. They tend to be overshadowed by Taurasi and Griner, but they definitely don't go unappreciated by Phoenix fans. Nor does Australian Penny Taylor, who was a key part of the Mercury's titles in 2007 and '09.

As for Chicago, the resilience award goes to reserve guard Allie Quigley. Four teams waived her over the first four years of her WNBA career, in which time she played in a total of 35 games. She didn't play in the league at all in 2012, but then finally stuck in Chicago in 2013. She has appeared in every regular-season and playoff game this season and last for the Sky, and her combined 54 points in the series against Indiana were crucial for Chicago.

The Sky also have gotten a big boost from forward Tamera Young, in her sixth season in Chicago, and guard Courtney Vandersloot, who has made strides and overcome injury in her fourth season in the WNBA.

Ultimately, the pivotal figure in this series might be Taurasi, the runner-up to Minnesota's Maya Moore as the league MVP this year and one of the most accomplished players in women's basketball history.

Taurasi, who won three NCAA titles while at UConn, is trying to add a third WNBA title at Phoenix. Her performance in Game 3 of the West finals against Minnesota on Tuesday was a Taurasi tour de force.

Phoenix has the home-court advantage and, for that matter, virtually every perceived advantage in this series. But the Sky have earned their spot, too, and now will see whether they can pull off another series upset.

It might not be a predictable WNBA Finals matchup, but it's still an intriguing one.