I always went with the 2 grade drop, I know that sellers will always fight for the higher price. So i went back and found the article.
So i went back to the "Sport Market Report" When it comes to pricing, there is no general rule that can be applied to cards that exhibit qualifiers such as OC (off-center), PD (print defect), or ST(stain). It really turns on the eye appeal of the card and the inherent difficulty of the issue. For example since a 1989 Upper Deck Ken Griffey Jr rookie card is relatively easy to obtain free of qualifiers, one of these cards would drop in market value significantly if any qualifier is present. The value would drop as much as 1-2 grades at a minimum, in terms of value. In other words, a PSA Mint 9OC would probably sell between PSA NM 7 and PSA NM-MT 8 value. On the other hand, there are issues that are so difficult in high-grade that the qualifier, depending on the type and the severity, would not lower the value greatly. For example a 1954 Wilson Franks card with an OC designation may not be severely affected since that issue is extraordinarily difficult to find nicely centered. In addition, the degree of the qualifier can also be a factor. A PSA 8OC 1933 Goudey Babe Ruth #144 that features 75/25 centering will usually carry more value than on featuring 90/10 centering. This is also true for other qualified cards, like cards exhibiting stains or print defects. Severity is the key. The more the qualifier hinders eye-appeal, the more the value will suffer.
So i went back to the "Sport Market Report" When it comes to pricing, there is no general rule that can be applied to cards that exhibit qualifiers such as OC (off-center), PD (print defect), or ST(stain). It really turns on the eye appeal of the card and the inherent difficulty of the issue. For example since a 1989 Upper Deck Ken Griffey Jr rookie card is relatively easy to obtain free of qualifiers, one of these cards would drop in market value significantly if any qualifier is present. The value would drop as much as 1-2 grades at a minimum, in terms of value. In other words, a PSA Mint 9OC would probably sell between PSA NM 7 and PSA NM-MT 8 value. On the other hand, there are issues that are so difficult in high-grade that the qualifier, depending on the type and the severity, would not lower the value greatly. For example a 1954 Wilson Franks card with an OC designation may not be severely affected since that issue is extraordinarily difficult to find nicely centered. In addition, the degree of the qualifier can also be a factor. A PSA 8OC 1933 Goudey Babe Ruth #144 that features 75/25 centering will usually carry more value than on featuring 90/10 centering. This is also true for other qualified cards, like cards exhibiting stains or print defects. Severity is the key. The more the qualifier hinders eye-appeal, the more the value will suffer.