As Atlanta United and MLS develop deeper knowledge and use of data analytics, we’ll be taking a look behind the curtain at some of the specific stats the club values. In our new weekly content series, we examine one metric provided by StatsBomb that may not stand out on a first watch, but upon closer evaluation, is a useful tool to measure the team’s performance. This is Staying on Track presented by MARTA.
Passing is an important facet of soccer. A soccer match can involve as many as 1000 passes per match. For example, Atlanta United’s most recent 2-1 win over New York Red Bulls on October 5, Atlanta United completed a total of 554 passes. The visitors completed 316. Comparing those two numbers, we can assume that Atlanta United dominated possession (they did, 62 percent) and were more efficient with their passing (true, 88 percent compared to New York’s 76 percent).
One way that data scientists measure skill and success with passing is a metric called expected pass.
The metric: Expected pass (xPass)
What it measures: How often to expect a pass to be completed based on the conditions of the pass.
Several factors go into determining the expected pass number:
- The start location of the pass
- The target distance of the pass
- The angle of the pass
- Whether the passer was under pressure from the opponent
- The body part used (foot, head, other, etc.)
- The pattern of play (open play or set piece)
For example, a short, simple pass intended for a player unmarked in a central part of the pitch is going to have a higher value than a long-range pass from a closely marked defender up the pitch to a striker who’s double-teamed.
One player who stood out because of his passing ability was Atlanta’s Ronald Hernández. The fullback earned a place in the starting XI for interim head coach Rob Valentino, filling in for Brooks Lennon on the backline, in Atlanta United's most recent match on October 5.
This was Hernández first MLS start this season since July 20, and the fullback didn’t seem to skip a beat. He finished the match ranked second on the team in total passes, trailing only his fullback counterpart Pedro Amador. He even took a few chances on goal, cracking some early shots that kept Red Bulls goalkeeper Carlos Coronel on his toes.
Hernández led the team in expected pass completions. He completed 95 percent of his passes and finished seven completions above expectation, an overperformance that turned out to be the best number for an Atlanta United defensive player all season.
Let's compare two specific passes that Hernández completes during the match:
These two passes require different levels of skill and represent contrasting expected pass numbers. The short pass to Alexey Miranchuk has a higher value. Miranchuk is unmarked and located in a central part of the pitch. Plus, the pass is short. (Although there is a little difficulty because the ball to Hernández arrives on a hop, and he's absorbing pressure from a defender. Both he does well to control.) The pass to Edwin Mosquera, on the right, is much more difficult. That one's a long pass on the ground. Hernández sends it across the pitch, through traffic and at a tougher diagonal angle, all conditions that make an expected pass number lower, less probable and more difficult.
The night was a big moment for a player who hasn’t been a regular starter for Atlanta United this season. Not only did he contribute to an Atlanta United victory, which was roughly 10 seconds away from a clean sheet, but Hernández also played a significant role helping Atlanta United be the more efficient side against a strong opponent that has competed for a top-four spot in the conference.
Hernández spoke about the moment Saturday after the final whistle:
“I feel really satisfied because I believe that when you work hard every single day, in and out, no matter the circumstance that you’re going through – you can be injured, you can be out – you always can bring something to the table. It’s not easy, but you just have to keep going. Take it one day at a time and keep working.”
Atlanta United's Data Scientist & Analyst Arjun Balaraman contributed to this video. Video and illustrations by Khoury Kennedy, Atlanta United's Motion Graphics Producer and Video Editor.
