One of things that bugged me early on when Band v2 launched was how someone, somewhere made an executive decision that overall, average pace should bump out current segment pace on the main Run screen for the device. Coming from Band v1, I noticed this right away. I remember my first run with Band 2, thinking how horrible my split pace was. I immediately considered that Microsoft may have released buggy hardware (not unheard of), until I realized that the default Main metric had changed between Band versions.
Overall average is a good stat with which to monitor active races (10k's, half marathons, and marathons), but not really a great tool for active pace improvement for training, or even for quicker paced 5k's. If you’re training for a race, or just want improve your segment/split pace in real time, switch the Metric on the Main Run screen from “Average Pace” to “Instantaneous Pace.” You'll thank me. Training to improve split pace holds a lot of benefit including increasing VO2 Max, improving blood flow, extending respiratory and perspiration efficiency, building better strength and endurance, and of course, finishing your daily minimum mileage in less time. You can always jump into the Microsoft Health web dashboard to view overall average pace anytime, but I prefer to watch active instantaneous pace in real time.
You can make this change in the Desktop Sync app (Windows and Mac), or in the Microsoft Health app on the smartphone (iOS, Android, and Windows Mobile). Open the app, locate the Manage Tiles option, find the Run activity, and tap or click the edit icon (pencil) to get access to the metrics options to modify.