To be fair - from my own simple analysis, you can get a feel for how skewed Riot's analysis is based off of this post where:
The number of people playing in premades is the highest we’ve seen in League’s history and 98.6% of the time, premades of 4 or 5 teammates are being matched against a premade of the same size (most of the 1.4% with more divergent premade sizes come from very high and very low MMR ranges). Teams made of solos and duos are matched against a premade 4 or premade 5 only 0.21% of the time, and players queueing solo get teamed up with 4 man premades 3% of the time.
98.6% of the time, premade 4 or 5s are matched up with premades of the same size. This can be interpreted three ways:
Let's take assumption 1, and while I believe this statement to be untrue, I'll assume it to be true to do a proof by contradiction. I'll state it once more, there is no way 4,1s (4 premade, 1 solo q) play against each other 98.6% when a typical solo q player plays with 3 4,1s in 100 games and only against .21 4,1s in 100 games. You can multiply this number infinitely because the ratio will still hold true. Now, this is the set of games where a solo q player plays. Let's reduce the set to the games of only 4,1s. Because all 4,1s MUST have a solo q player. We know that 4,1s only play 7% (.21%/3%) of the games against other 4,1s or 5s. This automatically contradicts the assumption that 98.6% of 4,1s play against only 4,1s which therefore rejects the initial assumption of interpretation 1, rejects 3 as well (if premade 5s were matched up less than premade 4s, then the percentage has to be less than 7%), and therefore the conclusion is interpretation 2. This is the only feasible explanation.
If this is the case, then they are manipulating data to be in their favour. The numbers aren't similar and combining them effectively skews the numbers they give out. It's hard to say what's statistically significant in this case, but you can't call this honest information - because it's not. It's carefully selected to prove what Riot needs - is this good? For a corporation it's absolutely necessary. Do I think it solves the problem at hand? No. It's effectively ignoring what the player base is asking for and is an attempt to cover it with a piece of paper they decided to brand as a bandage.
Tweaking numbers, and skewing them to fit the results you need is almost the same as fabrication. Yes, they are trying to calm a gigantic fire they created by removing solo queue, but I find it disappointing they're using numbers they've skewed to make a point.
To see what this really shows, let's use an example that Nidalee and Syndra jungle don't need changes because the average win rate for Nidalee and Syndra jungles is 50%, even though Nidalee has a 60% winrate and Syndra is at 40% winrate. The combined numbers gives you an idea about the state of Nidalee, but what it really tells you is the state of Syndra and Nidalee. Just like we don't care about the state of the combined junglers, we don't really care for the combined stats of 4,1s and 5s. We care for them individually, and at different MMRs. The information they've given out is mostly irrelevant. It doesn't answer the question of how is the state of 4,1s or 5s, it gives us the state of them together which is useless, just like the Syndra + Nidalee winrate.