Casey is the classic target forward, capable of holding the ball with his large frame and capable of scoring in a variety of ways.
Cummings has blazing speed, impressive on-ball skills and strikes as good a cross as any player in MLS.
"It's difficult because they do compliment each other very well," Sounders defender Jeff Parke said. "(Casey) will do the brute physical work and then Cummings will be able to run at you, and do all the chasing and make you work real hard to get the ball of your foot. He'll be all over the field."
And yet, both players are struggling to find the form that made them the top scoring duo in MLS last season.
Although their combined totals of five goals and one assist may not seem that far off from the pace of their 24-goal, 13-assist season of a year ago, their 2010 numbers deserve some explanation.
- Neither player has registered a point since April 18, a span of four matches.
- Cummings' two goals came in the season's first two games, meaning he hasn't had a goal or an assist in the last six matches.
- All three of Casey's goals have come from the penalty spot.
Why, exactly, that is happening is a bit of a mystery. Cummings, at least, looks as fast as ever and his passing looks accurate. He's no longer playing up top with Casey, though, and is playing a more withdrawn position on the right side in a 4-2-3-1 formation. The move has given him more space, but hasn't necessarily led to more scoring.
That's left Casey as more of a lone striker and results would seem to indicate that teams have been relatively effective at limiting his effectiveness. Whether it's a coincidence or not, the change in formation occurred five games ago.
The impetus for the move, according to what Rapids coach Gary Smith told the Denver Post, was the desire to better utilize the skills of central midfielder Mehdi Ballouchy.
"Mehdi is at his best when he can show the athleticism and energy to his game," Smith said. "He's a very talented boy . . . I think he's only now starting to find what he's about, and the team are finding what he's about. It's given him more scope and better opportunity."
Ballouchy was coming off a season in which he was sixth in the league with seven assists, but only scored two goals.
In the last four contests, Ballouchy has equaled his 2009 goal total. One of those goals was the game winner in the Rapids' most recent match, May 8 at DC United.
"Ballouchy is a player that is more hot and cold (as compared to some of the other Rapids)," Sounders coach Sigi Schmid said. "But he's a player, when he's on, he can certainly put together some good combinations and he is dangerous on set pieces as well. I think we have to be aware of all that."
Other offensive threats that Seattle will have to keep an eye on are former U.S. National Team member Pablo Mastroeni, MLS veteran Jeff Larnentowicz and super-sub Colin Clark. The team is deep enough that former Designated Player Claudio Lopez rarely sees the field.
Despite all this fire power, the Rapids have been struggling to score recently, scoring just one goal in their past three matches.
That the Rapids (13 points in eight games) are still sitting in the middle of the playoff chase is a testament to their defense, a unit that is currently allowing nearly .50 goals fewer per match than it did last year.
Right back Marvell Wynne was probably the most significant backline addition during the offseason. Wynne has to be one of the fastest players in MLS and whatever he lacks in on-ball defending, he more than makes up for with speed and strength. It is not uncommon to see an offensive player get a couple steps on him, only to see Wynne make up the difference in time to shut off the threat.
Wynne will provide the best challenge to date for Sounders left wing Steve Zakuani, who so far has had little trouble blazing past wing backs.
Rapids keeper Matt Pickens is also in the midst of his best season. The six-year MLS veteran is currently fourth in the league with a .88 goals against average and his .750 save percentage is tied for fifth best.
The Rapids defense has allowed six of their seven goals on set pieces -- two on penalties, one on a corner, one on a direct free kick and two more on indirect free kicks.
Although the Sounders haven't exactly shined in these kinds of situations, they have scored three times that way despite not having any PK opportunities. Fredy Montero has shown remarkable ability on free kicks within 40 yards and the service on corners has improved in recent weeks.
With Wynne and fellow projected backline starters Drew Moor and Danny Earls all coming off heavy-minute performances in Wednesday's U.S. Open Cup loss to New York and the Sounders coming off a feel-good win against Boca Jr., maybe this is the week it all finally clicks for the Sounders.