So ur concluding that without even knowing wether Garp fought him at his peak or not ....Because by the time Roger was at his strongest, he only had one man who could match him 100%. This man man whos known as Whitebeard became the strongest man after Roger's death. If we include that Garp could push Roger when Roger reached his prime to a near death, it wouldn't make any sense whatsoever. Reason being, the gap between Whitebeard and Garp was big enough that it is clear for anyone Whitebeard was stronger than him. This is also backed by the fact that even though Whitebeard lost more power than Garp due to illness, he was still the strongest man. Therefore, we can logically conclude that Garp was strong enough to do what Roger said, but couldn't do so at Roger's absolute strongest.
Nothing in manga suggestes that Garp out matched by WB exept his title of WSM even WB admitted that I can't be strongest forever....Lol
We are not going to change our minds anyway ...IMO WB would barely mange to win against Garp like Akainu did with Aokiji ...I don't think the Gap b/w them is any bigger than that....In fact Garp had a better chance of winning due to WB sickness and Garp is perfectly alright though we don't have enough knowledge on his powers so I'll go with WB...