It's pretty difficult to get a straightforward read on the effectiveness of your messaging and positioning but there are a few things you can do to ensure your messaging is more likely to succeed. 1) During the process of creating the messaging, work with your market research team to test aspects of the messaging with prospects and customers. This can be both quantitative test of words or descriptors you use as well as qualitative tests where you actually test aspects of a pitch with customer. 2) Get input early and often from your sales, customer success, and support teams. 3) Use A/B testing to evalute how the messaging resonates on your website, search, social copy.
Once you've created the messaging, you can use your channel metrics to track how well it's resonating but give it time. Any change of messaging takes a while to take hold with the audience (be it sales or customers) so don't be in a rush to make an update just because you see metrics dip initially.