This was about money. Callaway is willing to pay Els big money, just like they were/are willing to pay Mickelson big money. The reason being, they make their money on clubs, and are trying to gain a larger market share in the ball industry.
The best way to gain a larger market share in the ball market is to get the marquee players, basically copy what Nike did in basketball and every other sport, now golf to an extent. Does Nike make soccer shoes comparable to Adidas? Of course not, but Brazil is wearing their stuff.
Bottom line, Callaway is not made with Mickelson at all, and they were only too happy to sign Els.
Whomever compared Titleist to the Bears has something because that is their SOP, right now.
They do not pay DL III that much, and he is falling off, and they are content to run with Adam Scott right now, from a club perspective, in terms of marquee players.
But, Titleist knows their money comes from balls, and if they weren't going to offer Mickelson Callaway money, they certainly were not going to do anything differently with Els.