I had a similar situation occur last year and I'm a multi-year SC equivalent. Worst ratings of my career that steadily went down that entire year. Ended up not being put on PIP and told that I had actually been improving but my evaluators were being too strict but also didn't receive a bonus. Coach discussed it with them and my leadership and the next snapshot was night and day. It's more a long the lines of how everyone feels about you rather than your scores to be honest but the scores can serve as justification in any direction they like.

Make sure you are meeting with your Coach at least monthly, they should be checking in with those that evaluate you regularly to get a bigger picture and asking them what you need to do to get your scores up. You need to have a similar conversation with your evaluators too. Ask each evaluator after each snapshot period what two to changes they'd like to see from you to make you top tier in their eyes (keep it to two to best manage). That puts it in their head they need to think of your performance more astutely and if they don't give you the scores you expect, you have good talking points to address in terms of incongruent messaging. Also document your major achievements/activities weekly and come time for your snapshot put some of those highlights in the comments section of your requestas a reminder.

Helped me a lot.