Verizon (VZ -1.10%) and AT&T (T -0.67%) have based their marketing on the idea that they have better networks than Sprint (S) and T-Mobile (TMUS -0.40%).

Ads like the current "A Better Network As Explained By Colorful Balls" from Verizon tout network superiority citing the twice-annual survey done by RootMetrics. This is not the only national report on wireless networks -- OpenSignal does one using real-world user data rather than its own testing -- but it's the one which generally garners the most attention.

That's probably because RootMetrics actually declares a winner. For the last four reports that winner has been Verizon with AT&T coming in a clear second. The latest report, which was released Feb. 18 shows the same two companies on top -- something they will almost certainly crow about in ads -- but who won does not really tell the whole story.

Source: Verizon 

What the report says
The Mobile Network Performance in the United States for the 2nd Half of 2015 found that Verizon still leads but T&T has become a clear number two. Verizon took first place Network Reliability, Network Speed, Data Performance, and Call Performance while AT&T scratched out a small win in Text Performance.

"Other networks are making improvements in an effort to close the gap, but Verizon continues to lead the pack," wrote RootMetrics.

Overall performance was a win for Verizon again. Source RootMetrics

Putting the results in perspective
While Verizon and AT&T can continue to justifiably claim network superiority, the reality is that their lead is actually not as impressive as it seems because all four networks have improved dramatically. RootMetrics Vice President Julie Dey explained some of the results in an email to The Motley Fool.

"The data in our latest National Report reveals meaningful changes to the mobile landscape: Carriers have continued to add capacity, and expand their LTE footprints, which in turn is resulting in improved reliability and speed for consumers," she wrote."Verizon and AT&T continue to lead the rankings but all four networks are getting better, especially when it comes to data speed and reliability where we've seen improvements across the board. Particularly in metro areas...This is excellent news for consumers as these are two factors that have a big impact on the day-in and day-out mobile experience for consumers."

Dey's most interesting observation might be calling Verizon and AT&T "largely neck-and-neck at the national level" while also praising T-Mobile and Sprint.

"Sprint and T-Mobile continue to trail the top two during this round of testing but are showing real improvements," she wrote. "For instance, Sprint won second place outright in call performance at the national level and increased its call performance awards at the state and metro levels over the previous half. Furthermore, T-Mobile improved in speed and reliability, gaining more speed and data awards especially at the metro level. These improvements, combined with expanded LTE coverage, suggest we could see real changes in the first half of 2016." 

Unlike previous years when the third and fourth place carriers were well behind, this is more a case where there are leaders, but there is no shame in coming in last. It's probably worth nothing that T-Mobile CEO John Legere does not agree with that (or the RooMetrics testing methodology) and he sent an email to media on the day the report was released detailing his problems with it. 

How it works
RootMetrics does its own testing. According to the report, that involved driving over "231,000 miles while testing performance on highways and in big cities, small towns, and rural areas across the U.S." To compose the study researchers collected approximately "3.8 million test samples while testing performance while driving, at stationary outdoor locations, and at more than 6,600 indoor locations."

The company calls its findings "comprehensive, unbiased results that you can trust to give you a complete and accurate picture of mobile network performance across the entirety of the United States." It also noted that the report is weighted by population density so "results from more populous states like California carry far more weight in our national results than those from less populous states like Rhode Island. In addition within a state large metro areas carry more weight than small towns or connecting highways.

See the full methodology here.

What does it all mean?
Verizon and AT&T can continue to base their ads around having the top-rated networks according to RootMetrics. But, while those claims are accurate, Verizon's "Better Matters," slogan has never been less true.

For someone who travels extensively, especially in less-populated areas, an argument can be made that going with Verizon or AT&T makes sense. But, since most people don't do that and most live in heavily populated areas, in reality Sprint and T-Mobile are usually good enough.

The overall quality of wireless networks has improved so dramatically that for the majority of Americans, these results have become shades of difference that do not matter. All four companies are pushing to meet the increasing data demands of consumers and they are mostly succeeding.

Yes, Verizon still has the most balls, but this is not a race where only first place counts. Ranking numbers one is nice, but if third or fourth comes pretty close while charging less, well, in wireless networks that's a victory too.