Broad band transmitting glasses from visible to mid-infrared with good mechanical strength, chemical durability, glass-forming ability, and thermal stability are preferred for optics and laser technology applications. Generally, low phonon energy glasses possess an extended transmission cutoff toward mid-infrared, but at the same time, retention of other desired properties is challenging for the researchers. In this work, we have shown that mixed alkaline earth (Ba/Sr) would have the potential to improve overall glass properties while retaining its low phonon energy when CaO is partially substituted by BaO/SrO in calcium magnesium zinc silica-aluminate (CMZSA) glass. Quantitative structure analysis of its role in glass properties has been carried out using molecular dynamics (MD) simulation and experimental techniques. This study reveals that Al and Si mainly attained fourfold coordination, while Zn and Mg majorly existed in Al-O-Zn/Mg triclusters. The Ba2+ ions play almost equal roles as charge compensators and network modifiers, while Sr2+ ions play a larger role in charge compensation. As a result, the SrO-added glass leads to the highest bridging oxygens as compared to others and corroborates with improved optical, thermal, and mechanical properties. Hence, the SrO-added glass shows the most stable network connection and improved overall glass properties.