Actually, it was never stated explicitly that Garp always lost.
Crying? I didn't see any tears coming from his eyes. How did you manage to read the panels and then type the word "crying" with a straight face?
Now if it was shouting? Sure. Of course he would need to shout in order to emphasize the danger of what his DF can potentially cause and let his soldiers hear clearly. Why would he stay nonchalant and be soft spoken? lol
Again, Roger isn't way superior to Sengoku and Garp. Sengoku managed the Marines longer as a FA longer than Gol D. Roger did with his crew as a PK luls.
Shiki is pure ass. He is strong but you are like overestimating the shit out of him. This dude's goal was to showcase the might of the pirates but was sidelined and became an irrelevant character after being assaulted and manhandled lol. Really though. How long has it been? Does he need more than 20 years to prep or something? If he was THAT powerful, he wouldn't need to prep that long.
Seriously though. If Shiki was remotely as strong as you suggested then he would have contended with the other emperors in the past because he would already be ready to show his "might" to the Marines.