The best case for all of these cards is probably Edric, Spymaster of Trest, which held steady at around $4 with very fringe legacy play, until it ended up winning a SCG open last April and spiked to $15 overnight (before getting reprinted in Conspiracy a few months later and dropping dramatically)
The problem the three cards all have is delve ended up being a bit overpowered as a mechanic, so just the mechanic coming back is a longshot, making these three reprints an even bigger longshot
There are comboing Dragons, Vampires with incredible protection, and Merfolk that accrue so much card advantage that it can be staggering
He tries to understand his own internal flaws and works to improve them"
But there will also be games where the thing thats wrecking your plans has an even cost
For example, take the Magic booster