Why does Homes think that the things found at the murder site are not strong evidence in act 1 scene 1 to 8.

What arguably makes the Sherlock Holmes collection so appealing is that readers have the opportunity to play detectives as well, using Watson as their stand-in to survey the evidence and then see if they can figure the case out. Here the evidence can be easily summed up: the dead body, shot close-range by a sawed-off American shotgun; a stain of blood on the windowsill; muddy shoeprints near the windowsill; one dumbbell; a mysterious card near the body; a missing wedding ring; reports of the timing of the shot; a bicycle in the hedges. Holmes is thinking these clues are rather generic and has trouble fitting them together.