I found a workable solution to the problem, though I am unsure if it's the most efficient way. First, I established a Saved Search called "Event Stats By Host" for calculated value. The time range was set from -30d@d to @d. Accelerate this search is checked with a Summary range set to 1 month.
index=myindex | bucket span=1d | stats dc(eventid) as idCnt, sum(eventCnt) as eventsPerDay by _time host
Next, I conduct searches to compare yesterday to a 30 day average and calculate deltas:
|savedsearch "Event Stats By Host" | stats latest(_time) as _time,latest(idCnt) as lidCnt,avg(eventsPerDay) as aEventsPerDay,latest(eventCnt) as lEventsPerDay | eval eventCntDelta=lEventsPerDay/aEventsPerDay | table _time lidCnt aEventsPerDay lEventsPerDay eventCntDelta
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