Facebook click ID and email address are the two parameters that have a high priority which helps Meta match the users. Other parameters do matter but are of medium and low priority.

The best way to improve your EMQ score is to sync the first-party customer data with all these parameters through Conversions API and Meta Pixel. This helps Meta match the events accurately and in turn, increase your EMQ score.

EMQ is graded based on a comparison of the event match quality score (out of 10) with other advertisers similar to you in your region. Therefore, if you have an OK EMQ grade despite having an EMQ score of 5, that means your competitors or similar advertisers have a higher EMQ score way more than 5.

Meta Ads use External ID to identify the users. It is of medium priority for Meta to match and calculate the event match quality score.

Meta recommends having a higher EMQ score to increase the ad campaign performance. Yet, you need not be worried about it if you are sending the external IDs, and the click IDs for most of the users. External ID is used for deterministic matching by Meta.

Not to worry if your EMQ score is low just because of less % of fbc or Facebook click ID. Because fbc is present only for the users who land on your website from Meta Ads, if you figure out that only less traffic is from Facebook Ads, then it is totally okay not to have less % of fbc for your events.

Understanding EMQ is important in helping Meta identify the events with the users in its accounts center. Better matching of events helps you attribute conversions to your ads. It also helps in training the ad algorithms with relevant high-quality data and targets the people who are more likely to convert, which can result in better ad performance and lower cost per action.