Use an internal scorecard, to enable cross channel comparisons. Your internal scorecard is simply a way of identifying what metrics and measures that drive value for you. Spending more time upfront to develop this, pays dividends down the line.
Then for each media channel, comparing it against your internal scorecard. Creating benchmarks of expected performance. And also developing a habit of trying to predict success.
For each initiative, using your own data, to go, we think this work will deliver between X and Y. As a way of getting your team to think more strategically about the work and identifying where there is dissonance around what could be achieved and what actually is.
These behaviors will help improve performance.