Sure, the Colorado Rapids walked away with a hard-earned point in Saturday night’s 3-3 draw with the Philadelphia Union, rallying from a 3-1 deficit in the second half to collect the positive result. But make no mistake about it, the alarm bells are ringing loud and clear along the Rapids’ back four.

In their last four MLS games, Colorado have allowed a total of seven goals – high, but perhaps not too particularly alarming. But if you include two goals allowed in each of their US Open cup matches, including a 2-1 home loss on June 23 to the Atlanta Silverbacks in which head coach Pablo Mastroeni blasted his defense for allowing two “brain-dead” goals, something is clearly amiss on the back line.

Those mistakes were evident early and often in Saturday’s draw, and for Mastroeni, aside from Sheanon Williams’ 31st-minute goal off a corner kick, the defensive struggles stem from Colorado's deficiencies when they have the ball, as turnovers in bad spots put the back line under pressure.

“I think that set pieces should be the easiest thing to defend, because the ball is static when you’re defending it, so that’s a concentration issue," Mastroeni told reporters after Saturday's game. "I think what we’re discovering is that we are our most dangerous opponents when we have the ball.

"When we have good possession and we’re pushing teams back, we can’t be loose with our touches, [because] everyone is going to be pulled out of position. So like I said, it’s a bit naïve from us, and it’s going to be a part of our development, and we have to get better at it.”

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Changes have already started, and more could be coming soon. Left back Chris Klute, a regular through most of last season and this year as well, has struggled, and he was on the bench for Saturday’s draw, replaced by veteran Marc Burch.

Shane O’Neill’s youth was evident on a late tackle against Danny Cruz that drew a perhaps lenient yellow card and when O'Neill was beat by Williams for the second goal. Finally, rookie defensive midfielder Jared Watts made two miscues on the third goal.

Mastroeni is aware of the youthful struggles, but he also believes that time will help fix some of those errors.

“Obviously we have a long way to go,” Mastroeni said. “I think at times we are a bit naïve defending. We didn’t do a good enough job of defending. We made it difficult for ourselves when we had the ball and we lost possession in bad spots.

"But I think that those are growing pains that are going to happen with a young team and a young coach. We just have to keep working.”

Chris Bianchi covers the Colorado Rapids for MLSsoccer.com.