(CNN) Monmouth University's latest national poll of the 2020 Democratic nomination is sure to have folks buzzing. It finds a top tier of Vermont Sen. Bernie Sanders at 20%, Massachusetts Sen. Elizabeth Warren at 19% and former Vice President Joe Biden at 19%, down from 32% in Monmouth's last poll in June.

So does Monmouth's poll mark a turning point in the Democratic race for president? Or is this merely an outlier that later polls won't back up? My inclination is to say that it's an outlier and to pay attention to the average, though the truth is that we just don't know.

Let's place the Monmouth poll into context of what other polls have found.

If you average Monmouth's poll with the three other high-quality national polls taken this month from CNN/SSRS Fox News and Quinnipiac University , you get a clear Biden lead: Biden at 28%, Warren 19% and Sanders 14%..

When you break it down further, you see that Monmouth did not poll at a vastly later date than others or among a different set of voters.

Monmouth conducted its poll on August 16-20 among voters who say they are Democrats and independents who say they lean toward the Democratic Party.

Interestingly enough, CNN did its own poll of the race August 15-18 among this same defined group. Unlike Monmouth, CNN put Biden up with 29% to Sanders' 15% and Warren's 14%.

The CNN poll looks a lot more like other polls of the race taken this month when it comes to Biden. Fox News was in the field from August 11-13 (within a week of the Monmouth and CNN polls) and showed Biden at 31%, Warren 20% and Sanders 10%. Unlike CNN and Monmouth, Fox didn't preassign voters to the Democratic primary based on party identification. Instead, they asked all voters which primary they'd vote in.

Fox News' poll mirrors a Quinnipiac University poll taken from August1-4. Done among the same subset of voters (Democrats and Democratic-leaning independents) as CNN and Monmouth, Quinnipiac found Biden 32%, Warren 21% and Sanders at 14%.

You'll note that in all of these other polls, Biden's doing at least 10 points better than he was doing in the Monmouth poll. It seems unlikely to me that Biden lost so much ground within the two-day period of CNN ending its own poll.

And note that even the best pollsters have outlier results one out of 20 times.

Still, there are reasons to think that maybe Monmouth is closer to the truth than might appear at first glance.

First, the only real difference between Monmouth's poll and others is that Biden is down. The Monmouth results for Sanders and Warren are within the margin of error of the other polls. Warren's at 20% or 21% in three of these four polls listed above, and the one poll she isn't at 20% or 21% has her within the margin of error of 20%. Sanders' average across the four polls is 15%, and each poll result has him within the margin of error of that average.

Second, there are other polls that don't meet CNN's standards that show similar results to the Monmouth poll. While we don't report on those polls for a slew of reasons, it does suggest there is a universe in which Biden isn't doing as well as well as some other polls have found.

Third, Monmouth is a very good pollster . Maybe Biden really has lost a lot of ground or maybe he wasn't that strong as other high-quality polls have found. After all, Warren does seem to be generating a lot of enthusiasm (see her crowd in Seattle ).

Again, my best advice is to average all of these results. It's the advice you'll be hearing me say a lot over the next year. When so many polls are being taken, we're going to get some differing results from time to time. The average won't always be right, but it'll be right more often than not.