In the three weeks since she signed the first-ever million-dollar contract in women's professional softball, Monica Abbott and the Houston-area Scrap Yard Dawgs have been gaining momentum toward their inaugural season in the National Pro Fastpitch (NPF) league. May 31 marks Opening Day for NPF, which began as a six-team league back in 2004 and has since showcased some of the greatest softball talent in the world -- from former Olympians like Abbott, Jennie Finch and the recently retired Cat Osterman, to veteran Sarah Pauly of the Akron Racers, the winningest pitcher in NPF history.
Today, just one of the original six NPF franchises remains, but with the addition of the Scrap Yard Dawgs for the 2016 season, NPF has again become a six-team league. Each club plays a 48-game schedule from late May through mid-August, when the quest for the Cowles Cup begins. The championship trophy is named after former Utah State University softball player Jane Cowles and her parents, who helped establish the professional softball league that morphed into NPF. Major League Baseball supports the league as a development partner.
So, with just a handful of days to go until softball's top tier players take the field across the United States, let's take a look at each club and the stars that should make the 2016 NPF season appointment viewing.
Akron Racers

Home: Firestone Stadium; Akron, Ohio
Key fact: Established in 2004, the Racers are the oldest existing NPF club.
What you need to know: The Racers finished in third place in 2015 despite leading the league in several offensive categories, including walks (155), runs (188) and home runs (49). Outfielder and University of Georgia product Taylor Schlopy also led the league in the latter mark, slugging 10 longballs of her own. Fellow Georgia Bulldog Alex Hugo, a second baseman, joins the team for 2016, as do Jailyn Ford and Sami Fagan, the No. 3 and 4 overall picks of the 2016 NPF Draft, respectively.
Stars to watch: Ace Sarah Pauly, who joined the Racers for the 2015 campaign, is prepared to dominate NPF hitters for her 11th season. Last year, Pauly became the first NPF pitcher to record 100 wins, and she consistently sits atop league pitching leaderboards.
Chicago Bandits

Home: The Ballpark at Rosemont; Rosemont, Ill.
Key facts: Founded in 2005, the Bandits count former USA Softball national team members Finch, Stacy May-Johnson and Tammy Williams among their alumni. Since 2011, they have played at The Ballpark at Rosemont, the first facility in the nation built specifically for women's professional sports.
What you need to know: After finishing in second place in the 2015 regular season, the Bandits defeated the Racers in the playoffs and took down the Pride in the championship series to claim the Cowles Cup. The team lost stalwarts Williams (shortstop) and Amber Patton (third base) to retirement and saw Abbott depart for the Scrap Yard Dawgs, but they've acquired three-year veteran infielder Jill Barrett, who led the Racers at the plate in several categories last season, to help fill the gaps.
Stars to watch: Outfielder and Chicago native Brittany Cervantes returns for her fifth NPF season, all spent with the Bandits. She earned 2015 NPF Offensive Player of the Year honors for her otherworldly .358/.507/.670 batting line.
Dallas Charge
Home: The Ballfields at Craig Ranch; McKinney, Texas
Key fact: The Charge joined NPF as an expansion team for the 2015 season.
What you need to know: Dallas is a young club, as no player on its roster has more than four years of professional experience. Newcomers include Cheridan Hawkins, the first player in Pac-12 history to earn the conference's Pitcher of the Year Award for three straight seasons, and Mizzou speedster Taylor Gadbois.

Stars to watch: Pitcher and first baseman Lauren Haeger seeks to build upon a fantastic 2015 showing that encompassed both her college career and her NPF debut. The University of Florida graduate led the Gators to back-to-back Women's College World Series titles in 2014 and '15, and last year racked up numerous accolades for her efforts, including the 2015 College Softball Player of the Year and 2015 WCWS Most Outstanding Player awards -- joining Danielle Lawrie (sister of White Sox third baseman Brett Lawrie) and Keilani Ricketts (USSSA Pride) as the only players in NCAA softball history to do so. Haeger also finished her collegiate career as the only pitcher ever to win more than 70 games and blast 70-plus home runs. Upon joining the Charge, she proceeded to rank third in NPF in strikeouts (86) and innings pitched (97.2).
Pennsylvania Rebellion
Home: Consol Energy Park; Washington, Pa.
Key fact: An expansion team for the 2014 season, the Rebellion used the first pick of that year's draft to select Arizona State pitcher Dallas Escobedo, who recorded the franchise's first win.
What you need to know: Pennsylvania has struggled in its first two seasons of existence, finishing in last place both times. But with the veteran Escobedo returning to the mound and power-hitting catcher Lexie Elkins joining the lineup, the Rebellion hope that having the No. 1 draft pick in two of the last three seasons can finally pay dividends. Slugger Stacey Porter, a member of the Australian Olympic team and a professional softball player in Japan, should also be a boon on offense.

Stars to watch: It's difficult to pinpoint one clear star on the Rebellion's budding roster, but Alisa Goler and Kristyn Sandberg, the 2011 and 2012 NPF Rookies of the Year, respectively, have certainly made names for themselves. Sandberg ranked fifth in the league in on-base percentage (.402) last season, while Goler smacked eight doubles, fourth best in NPF.
Scrap Yard Dawgs
Home: Scrap Yard Sports Complex; Conroe, Texas
Key fact: General Manager Kevin Shelton, who held the same role with the Charge in their inaugural season, will oversee the Dawgs throughout the 2016 campaign.
What you need to know: The fledgling club has high expectations for itself, thanks in large part to the addition of Abbott, who is by far the most senior player on the roster. But Nerissa Myers and Madison Shipman, the 2014 NPF Offensive Player of the Year and Rookie of the Year, respectively, are both signed through 2018, proving the franchise's commitment to long-term success. Rookie Kiki Stokes, the sixth overall pick this April, has the potential to follow in their footsteps.

Stars to watch: Abbott, the 2015 Cowles Cup MVP and professional softball's first million-dollar player, brings eight seasons of NPF experience to the first-year club. While with the Bandits last season, Abbott was one of just two pitchers, along with Cat Osterman, to strike out more than 100 batters (149), and she allowed just five runs over the entire season to post a minuscule 0.31 ERA.
USSSA Pride
Home: Champion Stadium at ESPN Wide World of Sports; Orlando, Fla.
Key fact: The Pride have won three championships since joining NPF in 2009.
What you need to know: NPF's Florida club finished with the best record in the league last year at 34-14 and had hopes of clinching a third straight title but dropped the championship series to the Bandits. Now that Osterman has hung up her spikes, the Pride will look to freshman Kelsey Nunley, the 2015 SEC Pitcher of the Year, to bolster the pitching staff. Despite the loss, the club still boasts plenty of experience, returning outfielder Kelly Kretschman, the NPF's Most Outstanding Player in 2015, as well as shortstop Shelby Pendley, the reigning Rookie of the Year.
Stars to watch: Expect Lauren Chamberlain, the first overall draft pick in 2015, to break out during her sophomore campaign. After shattering NCAA records -- she crushed 95 home runs and slugged .960 -- during her tenure at Oklahoma, Chamberlain popped five longballs during her first season with the Pride. But the 5-foot-9 infielder certainly has the power to contribute in a big way.

Tune in throughout the summer as National Pro Fastpitch plays its 13th season, with 23 games scheduled to air nationally on CBS Sports Network and more than 100 streaming live on NPF's exclusive digital platform, NPFTV.