Various stiffness characteristics of removable and replaceable absorbent core components used with disposable absorbent articles are disclosed. The replaceable core component can be constructed with bending stiffness characteristics making it easier to install in a diaper chassis. In other instances, a relatively stiff insertion tool may also be used to engage a relatively flexible replaceable core component to aid with insertion of the replacaeable core component into the diaper chassis. Aspects of the present disclosure involve replaceable core components alone or in combination with insertion tools having bending stiffness characteristics that reduce the likelihood of buckling and/or folding while installing the replaceable core component into the diaper chassis. The present disclosure also provides methods for testing replaceable core components and/or insertion tools to evaluate the bending stiffness characteristics associated therewith.