As many know, more have likely guessed, few will care about and almost all at least were surprised about, I have been dabbling in team play the last few weeks. this morning I decided I had enough scores in both styles to take a look and see what effect it's had, as this is often a matter of interest and contention.
My teaming has been twofold: BB-SD on Tuesdays (sometimes GD too) with an established, already decent if not quite elite team that was until very recently at BWW Green River. There were a few strong players, one very strong, and a few occasional helpers there already.
Then Wednesday Six at Beef O'Brady's Newburgh, which is essentially Legend, myself and my wife with a few (different to Tue and not quite as useful) occasional helpers. The Tue team very recently moved there too - quieter and better boxes.
Last week in May for SD, and June for Six was the change.
Nobody is ever going to say I was the greatest at any of the three games solo, but, at least for BB and Six, few can honestly rate me lower than "pretty good" I would hope. Obviously, the better the player, the less boost they get from teaming - just ask Spotes about the massive effect my help had on his paltry medal count

Here's the results (I included Thur Six too because even though no team then, the wife and I have mostly kept sharing for that game since the move, and a helper or two will throw in an answer from time to time. Some solo efforts in there, but no way to isolate):
Six post teaming avg: 54351
Six pre teaming: 50451 7.7% gain
Showdown post: 49794
Showdown pre: 31553 57.8% gain
BB post: 12221
BB pre: 11139 9.7% gain
Clearly the big shift is SD, with its massively weighted to no-clue scoring and possibility of losing major points. The big difference it's made for me is more the much reduced chance of getting the final tragedy wrong than the (very real however) more questions right on other rounds. From long history of playing SD alone. I would honestly estimate my average if I got the last one right in the very low 40s.
The greater boost in the other Tue game is likely due to the more mature (as a team - although there are a few greybeards) and deeper bench-strength team. Legend is indeed a capable player, and my wife is fairly strong too, but they don't add up to the 4 or 5 decent players on Tue. It's a little counterintuitive maybe in that there is a very very pronounced overlap in the BB expertise of myself and the Tue team's strongest player, Dragon. We are both strong on the same topics, although he is clearly superior on the finer points of history and geography, whereas I may have a bit of an edge on fine arts. The Six effect is very different, as Legend's strength is one of my weakest areas - sports.
Overall a bit LESS of an impact than I would have predicted, except in SD of course, while still being definitely significant in both statistical and ranking terms. Again, the impact will vary with the ability of both the soloist and the team of course. Trying for a tournament or two in the past with me and a few hapless button-pushers gained me little and them a great deal, whereas adding just about anyone to 86th Street at full strength will not change much, but it's a definite indicator that even fairly strong soloists will see significant boosts with even a small number of useful teammates to fill in the gaps, validate good guesses to prevent second thoughts, or warn away from bad ones to cause second thoughts.