Lots of good discussion and people have hit on some key points. Baldy is often underestimated - people have died in avalanches there.
One of the biggest gaps is around awareness. Assessing risk (avalanche or anything else) is a continuous process and learning what to look for is important.
The fact that there was an earlier naturally triggered (rock(s)) avalanche is a red flag that conditions may not be stable. The fact that it was on the same general slope angle and aspect as the area that the climbers descended should've added to the warning bells. A rock trigger is not all that different from a human trigger.
Snowpacks do not generally like rapid or extreme changes - heavy loading from new snowfall, rapid temperature rises, wind loading, etc. These tend to contribute to instability.
The mountain and snowpack can give you lots of clues if you know what to look for. Only you can interpret what those clues mean. Kudos to many of you who noted those clues and made decisions to change routes, etc. People on Baldy are at a high risk of falling into heuristic traps (see second link below) and need to be aware of that as well.
Taking an level 1 avy or even awareness course is worthwhile. There are some good online references people should consider checking out including: Avalanche.org Avalanche News USFS National Avalanche Center
(also click on the section (left hand side) titled "Red Flags")