Clearly, improving outcomes and plan metrics is a constant pursuit among plan providers.

Joe Ready, director of Wells Fargo Institutional Retirement and Trust, acknowledges that it can be hard to move the needle when measuring plan performance.

But in this year's Driving Plan Health survey, which measures the trends, and ultimately, the performance of the more than 5,000 plans serviced by Wells Fargo, Ready says communication and plan design initiatives undertaken in recent years are starting to yield measurable outcomes.

"In the retirement plan industry, it sometimes seems like it takes a long time for the results of our everyday efforts to have an impact," writes Ready in this year's report. "Still, what I've noticed recently is that when we step back and look at where we are today, the progress we're making is quite remarkable."

Over the past five years, the participation rates, contribution rates, and diversification of participants' assets—the three metrics Wells uses to score a retirement plan's overall health—have improved for plans serviced by the firm.

Here is a look at 10 data points from the Wells Fargo 2017 Driving Plan Health report that Ready and his team think can be used by sponsors and advisors to measure plan performance and perhaps even the effectiveness of incumbent providers' services.

1.  Participation rate increased

 The participation rate across plans services by Wells has increased by 18 percent over the past five years. The number of participants saving at least 10 percent of salary, when accounting for the employer match, has increased by 9 percent. And the number of participants with a properly diversified investment strategy—one that is in line with the allocation strategy of a typical target-date fund relative to a participant's age—has increased by 15 percent.

The improvements in those areas have led to a 40 percent increase in Wells' Plan Health Index for all of the plans serviced by the firm.

2.  Auto-enrollment plan participation up

 Average participation for plans with automatic enrollment is above 80 percent, while plans without it have less than a 50 percent participation rate.

3. Higher default rate doesn't affect opt-out rates

As seen with data from other record keepers, that most common default rate in Wells Fargo plans is 3 percent. That can negatively impact overall contribution rates, a trend also seen across industry.

But data from the Wells Fargo universe shows that setting a higher default rate does not materially impact opt-out rates. The average opt-out rate for plans with a 3 percent default is 11.1 percent. For plans with a 6 percent default, the average opt-out rate is 11.3 percent.

4. Auto-enroll affects millennial participation

Among millennials, the participation rate for plans with auto-enroll is 84.9 percent. For plans without it, the participation rate plummets to 37.8 percent.

5. Older employees aren't participating

Among Wells' clients, 52 percent of eligible participants age 35 or older are not participating in a plan—underscoring the value that automatic enrolling all employees, and not just new hires, can create for overall plan health.

6. Contributions of 10% or more aren't widespread

Fewer than 40 percent of employees in a typical plan contribute 10 percent or more of salary, the area of plan metrics that has seen the slowest rate of growth over the past five years. Wells Fargo uses the 10 percent contribution rate, and an 80 percent income replacement in retirement, as benchmarks for assessing overall plan health.

7. Employer match affects participation.

About 90 percent of plans serviced by Wells Fargo offer some type of employer match, which proves critical to getting to the 10 percent deferral threshold. For plans offering a match, about 46 percent of participants are hitting a 10 percent savings rate. For plans that don't, the number drops to 28 percent.

8.  A communications strategy helps participation but one strategy in particular works well.

Wells Fargo offers sponsors various communication strategies and education platforms designed to motivate higher contribution rates. 

Among the most proven strategies is what Wells calls "trigger communications"—communications tailored to specific participant milestones, such as age, or communications that reinforce positive savings habits, as well as communications directed at participants that show a need for more prodding toward better habits.

Wells Fargo says that sponsors who take advantage of more of these communication and education campaigns average 44 percent of their employees contributing at 10 percent or more, compared to just a 31 percent rate for plans that don't deploy the strategies.

9. There's a reason best practices are "best"

Wells says the difference in overall plan health between sponsors that deploy "best practice" features and those that don't is "striking."

Defaulting new enrollees at 6 percent in a qualified default investment alternative, coupled with an opt-out automatic increase feature, invariably gets more participants to the 10 percent contribution threshold.

The number of participants who reach a 10 percent contribution rate when best practices are used is nearly double the number when plans use automatic enrollment alone with a 3 percent default deferral rate.

10. Some older participants are over weighted in equities

Younger participants tend to have the most appropriately diversified portfolios, a fact explained by their higher default rates into QDIAs like target-date funds.

Among Gen Xers, 42 percent are over weighted in equities, compared to a typical TDF glide path for their age. And 52 percent of baby boomers are over weighted in equities.

11. Of course account balances depend directly on age, tenure, and income levels

Deferral rates and average account balances increase with age, tenure, and income levels—no surprise there.

For participants making more than $100,000 a year, the average account balance is $$226,092, and the average contribution rate is 10.6 percent of salary. For those making between $40,000 and $59,000, the average balance is $40,890, and the average contribution rate is 6.4 percent.