SCORING IN SOCCER IS HARD. It’s supposed to be that way and it's part of the game’s charm and why putting a ball in the back of the net warrants such great celebration. 

But for some teams in Major League Soccer, scoring goals appears to be really hard. And in the case of the Colorado Rapids, its bordering on impossible. Week four of the MLS season saw the Rapids and Philadelphia Union continue to struggle to put the ball behind the goalkeeper, FC Dallas stay undefeated; and Kaka remind us why he might challenge Thierry Henry as the best player to ever set foot in the league. 

The Rapids have now failed to score in all three MLS games this season after yet another scoreless draw—this one with the Houston Dynamo. That, of course, is the pessimistic view. For you glass-half-full types, the Rapids have yet to concede a goal, which means the club can rightfully claim to be undefeated. 

Last year the Rapids allowed a league-worst 62 goals so its defensive improvement should not be downplayed. But if Pablo Mastroeni's men can't find a way to put the ball in the back of the net, that defensive improvement will be for naught.

The Philadelphia Union are in a similar situation. Yes, the club put three past Nick Rimando two weeks ago but the team has yet to score in its other three games this season. This weekend the hapless Chicago Fire shut out Philadelphia,1-0, and the Union failed to put a shot on goal.

“We’re not creating enough offensively,” Union head coach Jim Curtin told reporters. “We’ve been limited by teams. We have to do a better job of creating chances.”

Ya think?

Philadelphia fans watching Orlando City’s 2-2 draw with Montreal saw a pair of former Union players find the back of the net. Jack McInerney scored for the Impact while Pedro Ribeiro, who was claimed in the expansion draft, scored for Orlando.

Ribeiro’s goal was assisted by Kaka and the two Brazilians teamed up again when Riberio set up Kaka with a nice run and perfectly slotted pass.

A former world player of the year, Kaka is definitely not treating his time in MLS as a holiday. He has two goals and an assist in four games this season and has played with effort and flair in each of them. Kaka has won a World Cup and played for some great AC Milan and Real Madrid sides but he seems as committed to succeeding with Orlando has he did with those storied teams.

WHO'S HOT?

Don’t look now, but the hottest team in MLS actually plays in Canada. And it’s not the team that made all the high-profile designated player signings nor is it the one that’s a game away from a spot in the final of the CONCACAF Champions’ League. With three straight wins after a season-opening loss to Toronto, the Vancouver Whitecaps now have the longest current winning streak in MLS.

This week’s 2-1 victory was particularly satisfying because it came at the expense of Cascadia Cup rivals Portland. And Vancouver won despite Octavio Rivero being held scoreless for the first time this season.

Robert Earnshaw, back in MLS after being cast aside by Toronto last season, made the most of his 87^th-minute substitution appearance by scoring the winning goal in stoppage time with a well-timed run to get on a nifty through ball from Perdo Morales.

At 3-1-0 the Whitecaps are now second in the Western Conference behind FC Dallas, the only team still unbeaten through four games. In a match where both teams were missing multiple players because of injury and international duty, neither seemed disappointed to split the points and move on. In a league as parity-driven as MLS, a four-game unbeaten streak is nothing to look upon casually. 

The only other unbeaten team? The New York Red Bulls. After an opening day tie, the Red Bulls have now won two straight after beating the Columbus Crew 2-1. In both wins Bradley Wright-Phillips registered a goal and an assist. 

If New York keeps this up, disgruntled fans might finally forgive general manager Ali Curtis for replacing fan-favorite Mike Petke with Jesse Marsch as head coach. (Who are we kidding?)

AND WHO’S NOT?

Caleb Porter is regarded as one of the brightest coaching kinds in American soccer and thought by many, including himself, as a likely successor to Jurgen Klinsmann with the U.S. national team. But if he doesn’t turn things around in Portland soon, that reputation is going to be suffer badly.

Porter, of course, came to Portland in 2013 after a banner stint in the collegiate ranks at Akron University where he made two College Cup appearances and won a national title while playing the most attractive soccer seen at the college ranks since Bruce Arena ran the show at the University of Virginia. 

And in his first season with the Timbers, Porter’s magic touch carried over as the Portland won the regular season Western Conference and finished two points shy of Red Bull for the Supporters’ Shield.

But the wheels fell off last year and a series of defensive lapses led to many dropped points—and no postseason—in 2014. The team tied its first three games of 2015 and are now winless in four after falling to Vancouver over the weekend. Porter and Co. now find themselves at the bottom of the Western Conference standings. 

It’s early and the club can leap back into contention with a win or two but more troubling is Porter’s inability to solve the Timbers' propensity for defensive lapses. Two weeks ago it allowed a stoppage-time goal to Alan Gordon in a tie with the Los Angeles Galaxy. On Saturday it gave up Earnshaw’s strike after the 90-minute mark. 

At some point that stops being a coincidence and starts becoming a pattern. Porter may be testing the length of rope being given him by owner Merritt Paulson. 

NATIONAL TEAM WATCH

One of the glaring weaknesses of the U.S. national team, not just against Denmark but in most games the past year, is an inability to hold the ball and create chances for the forwards. Clearly, the U.S. needs more in the midfield and several Americans in MLS showed this week and early this season that they have earned a look.

Harrison Shipp is stuck on a bad Fire team but the second-year man continues to show a combination of skill and creativity that suggest he could help the U.S. The Fire only have two goals this season—did we mention it’s hard to score goals?—and Shipp has scored one assisted the other Sunday against the Union. 

He also did this. 

“Harry's a player that sees the game a little differently than most players,” Fire coach Frank Yallop told reporters in an amazing understatement.

Shipp isn’t the only midfielder making a national team case for himself. Kelyn Rowe, whom we’ve endorsed previously for his national team potential, had a brace Saturday as New England finally got off the schnide. 

Despite Colorado’s scoring woes, Dillon Powers (who played with Shipp at Notre Dame) has been a solid two-way player and his 10 goals and 15 assists in his first two years is indicative of his ability to create. And a few more plays like this from Nick DeLeon and we’ll be clamoring for Klinsmann to give him a look too.

FUTURE NATIONAL TEAMERS

While the U.S. U-23 and U-20 youth national teams were in camp in Europe, some overlooked age-eligible players served notice they should be considered for future camps. 

Cristian Roldan was one of the stories of January’s SuperDraft when he slid from an expected top three pick to 16^th overall. The Seattle Sounders nabbed the former University of Washington forward and are no doubt glad to have done so. 

Roldan, 19, has reminded us why he was so highly regarded ahead of the draft, receiving consistent playing time on a contender. He came off the bench in both of the Sounders' first two games and then got his first career start against Dallas, where he put in a strong 61 minutes. 

Like Roldan, Real Salt Lake’s Jordan Allen is 19 and young enough for this spring’s U-20 World Cup. After missing almost all of his rookie year last season after microfracture surgery, Allen has come off the bench in all three of RSL’s games this season. On Sunday he scored a late game-winner against Toronto.

Tab Ramos has experimented with Allen at left back with the U-20s but he was an attacker in his one season at Virginia and he showed that prowess when he snuck into a bafflingly large gap in the Toronto defense and headed in a Javier Morales cross.

Neither Roldan nor Allen were part of the U.S. roster in January’s CONCACAF qualifying tournament but their consistent play should lift them back into Ramos’ consideration set.

Not all the news on the U-20 front was positive. Dallas midfielder Kellyn Acosta, who captained the U.S. in qualifying, committed a harsh tackle against Seattle and was ejected after 17 minutes. It was the first MLS appearance of the season for Acosta.

Brooke Tunstall is an American Soccer Now contributing editor and ASN 100 panelist. Follow him on Twitter.