OEM 12c - Why Do DataGuard Performance Metrics Not Work with Adaptive Thresholds

We want to use adaptive threshold metrics to monitor standby targets for Apply lag and Transport lag.  However, when working with advanced threshold management Dataguard metrics only appear under the "Time Based Static Settings".

Looking at the documentation for creating advanced threshold metrics base monitoring, it states that advanced threshold metrics only support certain categories of metrics; load, load type, utilization, and response.  The apply and transport lags are measured in seconds, and the graphs appear to support these kinds of metrics.  So why can they not be setup as adaptive Significance level or Percentage of maximum?

Here are some screen shots from our OEM showing the apply lag and redo apply rate.  they seem like they would work.