"I think there are some good pay drivers out there at the moment but, to my mind, there are probably too many teams that have to rely upon pay drivers and I think that's a little bit sad for the sport," he noted, "It's an indication that we've got too much financial pressure in the sport at the moment.
"I think you'll always have a few [pay drivers], but I think too great a proportion of the grid, in my opinion, has to rely upon that and that just tells us that we've got to work harder to bring costs down in the sport, because it does distort."
Ferrari's Stefano Domenicali, meanwhile, highlighted another issue that, in his opinion, affected the quality of the drivers on the grid.
"I agree what Christian said but have one point to add," he claimed, "The less chances that we give to drivers to test on the track, the more it's likely that we have drivers than can present themselves to a team with money to bring with them. This is why we are so keen to have some more testing, for them to make sure that they are able to show to everyone how good they are on the track, on top of how good they are in bringing money to the team."