Zlatan IbrahimovicEasily the most requested player following the Top50 post. Probably, because he was not on the list. That doesn't mean that Goalimpact isn't rating him, he is just not in the Top50. Main reason is that he dropped out of the list due to aging. Here is the chart.
The thick line shows the Goalimpact at that time. This is the original estimate not using any future games. Clearly, with hindsight, we may give him another rating, because his team outperformed or underperformed original expectations. The expectations on how good a Zlatan will be in future, are derived from the Peak Goalimpact (thin dashed line) and the aging curve of field players.
If the team results of all of Zlatan's games are better than expected by his Goalimpact, the PeakGI line will raise. It will do that whenever the player overachieves original expectations, independent if he passed his peak already or not. In the recent year, for example, his PeakGI raised because his performance dropped less than we would have expected given the typical aging effect in football. Since 2011, the peak rose nearly 15 points. Without that raise, his Goalimpact would have been 15 points lower than it is today, so 140 instead of 154 points.
To summarize, Zlatan is a world-class player that is gradually weakening due to aging. But this aging process is much slower with him than with the average football player. His current performance still is outstanding at 154.
Theo WalcottThe high rating of Theo Walcott raised some virtual eyebrows on Twitter. So this is how his chart looks like:
Theo was rated "world-class one day" since he was very young. Given his young age, he was still rated as "ok for Premier League, but not outstanding". But this is his actual performance and not his "potential performance" or "talent", which both were rated as very high. Walcott delivered as expected until 2012. Therefore his PeakGI was more or less stable and the Goalimpact rose along expectations given the aging curve. From 2012 on, the team strongly outperformed expectations when he played and hence his PeakGI rose consistently until it reached a level of about 190 when match outcome and Goalimpact were in agreement.
Back to the Twitter question of why Walcott is rated that good: Because the team consistently outperformed prior (already very high) expectations with him on the field.
Cristiano Ronaldo"Cristiano Ronaldo is only 21st? Lol, he would walk into any team of the world" was a typical comment. We understand the critic because he is one of the best players of the world (also in according to Goalimpact) and many see him as the best (also Goalimpact before the change of the algorithm). So why did he drop in the new algorithm?
He actually didn't drop in the new algorithm, he maintained the world-class level he obtained in his Manchester United times seamlessly at Real Madrid. Real's performance with him on the field was fully in line with these very high expectations and thus there was no need to raise or lower the rating.
"Yes, ok, but he was rated higher in the old version". True, the reason is that Goalimpact adjusts expectations for all players of the field. The new version rates Karim Benzema higher than the old. This, in turn, raises the needed outcome for all his team mates to increase their respective scores. Hence, with Benzema rated higher, his team mates including Ronaldo were rated lower. That said, Ronaldo is rated as absolute world-class and would also according to Goalimpact walk easily into any team of the world.
Karim BenzemaSo? And why is Benzema that good?
We can't answer that. Goalimpact just measures how good a team plays with the player on the field. It can't tell why a player is adding to the team success., because it does not even look on what he is doing. It just relates the team success to the player being present on the field. If we define a "good player" as a player that make his team have a very good goal difference, then Benzema is extraordinarily good.