In order to answer this research question, an experiment was made in 2 phases.
1) A live experiment with the creation of a "Virtual Soloist Groups" (rules here: https://fold.it/portal/node/993167#comment-27535)
Formed 04/18/2014, deleted 05/05/2014 (on request of several top players because this resulted in a perturbation of the "real" group rankings).
Group ranks after this period: prediction 12, design 13, overall 18.
Best ranks: 6th in puzzles 880 & 882.
2) What would have happened if a Soloist Virtual Group had been present on the latest 25 puzzles?
Taking the score of the best Soloist without group in 25 latest puzzles
Taking the corresponding rank and score from the group ranking
retaining the best 20 scores
Multiplying by 2 (Overall scores are based on 40 best out of 50)
Overall rank 7
Best rank: 3 on puzzles 946 and 962.
There is a positive bias compared to the first live experiment (where only volunteers soloists participated). It's possible that, in the time of the live experiment, players participating were more productive due to competition spirit (this would make a negative bias). A positive bias comes from the fact that many beginners might not want to join a group: "Virtual Soloist Group" would have relatively less experimented players. This has to be verified.
On a sample puzzle (961), there was 104 soloists players on a total of 188 'active players' (= who got positive score improvement): 55%. That means that the probability to win for a Soloist Virtual Group is much higher than for each individual groups. Number of active players of the top groups is given here:
On sample puzzle 961, current group ranked 7 in the overall list (Gargleblasters) and in this puzzle had only 7 active players (on a total of 22 regular players for this group). They did as good as the 104 virtual members of a "Soloist Virtual group".
Group production seems much more competitive than a sum of individual competitors.
(The homo oeconomicus of mainstraim neoclassical economic theory might not be as competitive as the theory supposes... Actually, selfish players have few to gain in groups, most of the commons being on the open access Wiky and public recipes. This suggests that working for a "common group gain" - and related group members recognition- is a high incentive for top Foldit players).