Editor's note: Although Sounder at Heart no longer has FanPosts, we still want to encourage contributions from our community like this one. If you would like to submit something, email us at firstname.lastname@example.org.
I really enjoyed the mailbag episode that focused on our points per game (PPG) when Cristian was on the field, but I think there are better stats to point out that the Sounders are A LOT better when Cristian plays.
Sounders fans all know the value of Cristian Roldan, but I just don’t think the broader MLS community gets it. He doesn’t put-up eye-popping goals and assists, but when he is on the field, good things happen. FBref has a stat that does a great job of summarizing exactly this, and I think we should all point to it whenever anyone gets confused about Cristian’s impact on the game.
The stat is the net goals (us-them) scored while the player was on the pitch (on a per 90 basis). If that were the only stat you looked at, it would be hard to differentiate one player from another across teams because if the team always outscores their opponent then all players on that team would similarly have good numbers. To look beyond this, FBref takes the net goals per 90 mentioned above and subtracts the net goals per 90 for the team when that player wasn’t on the pitch. So if a player has a net goals per 90 of +0.5 and the team overall has a net goals per 90 when that player is off the pitch of +0.3, the player’s On Field-Off Field Net Goals per 90 will be +0.2 (which is pretty good).
Of course, to deal with the fact that sometimes people just get lucky, you can create the same stat with xG instead of actual goals.
Combining those two stats together on a chart gives a view of the player that seems to be on the pitch when good things happen AND when xG also says good things are happening (upper right corner is good). By this measure Cristian is an incredibly valuable player for the Sounders this year, with the team scoring +1.81 more net goals per 90 when he is on the pitch vs. off. The xG number for Cristian is +0.74.
Yes, we have been playing really well this year with Cristian on the field and frankly, not that well without him. Something the PPG stats certainly show, but this stat also points out that our form often takes a dip as soon as he is subbed, even if we do manage to win the game. This was perfectly illustrated in the recent win over the Rapids, when the Sounders led 2-0 until Roldan was pulled and they had to hold on for a 2-1 win.
This stat is, of course, sensitive to sample size. If a player only plays a few minutes and we get lucky and score a few, their numbers will look great. Similarly, if a player is almost always on the field, then subs out for a short time, how the team plays without them can also swing dramatically.
So, to be fair, the chart below only includes players that have played a minimum of 500 minutes AND have also been out for at least 500 minutes so far this year (thus removing players like Jackson Ragen, Yeimar, Nicolas Lodeiro, Stefan Frei, and Albert Rusnák):
Since I know you are curious, I also looked at the entire league and how Cristian compares. He is No. 2 on goals and No. 75 on xG.
One other note, Messi is not on the chart above, as he has only played 247 minutes in MLS this year, but if he were on this chart his goals are +1.51 per 90 (less than Cristian) and xG is +0.85 (better than Cristian).
All data as of 9/28/23 from FBref.com
Eric Main is a Sounders fan based in Kirkland