How can physical appearance of Roger Clemens support that he hasn’t used steroids?

It is known by each baseball fan that Roger Clemens is charged with obstruction of justice. It is claimed that he has lied before Congress about administration of steroids and HGH.
Rusty Hardin pointed out that there was no any difference in physical appearance of Roger Clemens before, during and after his working with the trainer Brian McNamee. The attorney confirmed that this aspect was a proof that Roger Clemens hadn’t applied steroids and other performance-enhancing drugs.
Increase of muscle mass is usually utilized by federal prosecutors as proof that an athlete uses steroids or/and other related medicines. But this tendency was not used during the case against Roger Clemens. Nobody could claim that muscles of Roger Clemens demonstrated that he had applied steroids and HGH. It is one of differences between the case against Roger Clemens and that against Barry Bonds.
When it comes to the governmental case against Barry Bonds, prosecutors called many individuals in the trial that were able to testify that anabolic steroids promoted substantial changes in physique of this person. They claimed that intake of steroids led to increase of muscle size, enhanced size of the head and testicular shrinkage in Barry Bonds.
Thus, the defense attorney Rusty Hardin presented four photos of Roger Clemens. The pictures displayed physique of Roger Clemens, including the time when Clemens was working with Brian McNamee. Hardin noted that the pictures manifested that there was no difference in physical changes that could support that he took steroids and HGH.
The attorney Rusty Hardin claimed that the photos displayed just the process of ageing. The masseur Cheryl Redfern also claimed that she didn’t observe any changes in physique of Roger Clemens. Roger Clemens experienced neither back acne, nor abnormal development of breast tissue, nor dramatically enhanced muscles.
Phil Garner a former Major League Baseball player also confirmed that there were not any obvious changes in physical appearance and performance of Roger Clemens during working with Brian McNamee.
The Assistant US Attorney Steve Durham tried to discredit the affirmation about lack of changes in Roger Clemens’ physical appearance during the cross-examination of the former baseball player Phil Garner. He noted that while certain steroids enhanced muscle mass, others didn’t induce enhancing muscles. Thus, he confirmed that the pictures could display nothing about steroid use.
Federal prosecutors desire to take advantages in both cases: in the case against Roger Clemens and in that against Barry Bonds. While they affirm that changes in physical appearance of Barry Bonds manifest that he has applied steroids, lack of changes in physical appearance of Roger Clemens doesn’t prove that he hasn’t administered steroids.