For every guy that underperforms because of lack of pressure, there's probably a guy who performs better when he doesn't constantly have to worry.The potential problem with this approach is that some players under-perform on front loaded contracts as there is much less of a financial incentive to work as hard as they might if they are working for their next payday.
Solder is about an average starting LT (which is valuable), but he'll be 30 before the season starts, plays a position that there are very few guys playing at 32+, and has a significant history of concussions. He's definitely going to leave a hole - but he's exactly the sort of guy that you don't fight over in the free market.