WAR and the Rule 5 Draft
The Rule 5 Draft dates back over a century, and Retrosheet has a fair chunk of Rule 5 data. The Rule 5 draft as we know it began somewhere around 1965, so I took all drafted players since then and their WAR in the following years. As it turns out, the Rule 5 Draft is a market for more-or-less freely-available replacement-level talent.
Most years, 80-90% of one-time Rule 5 picks either don't play or accumulate 0 WAR. That means that in the first year after being drafted, 35% don't play, while 55% occupy a Major League roster and play at replacement level. Five years removed, 70% of Rule 5 picks aren't playing, but at least most of those who do are competent Major Leaguers.
Many Rule 5 picks don't play for the team that drafted them. For example, Bobby Bonilla was a Pirate before he was taken by the White Sox, but he was traded back to Pittsburgh before he became Bobby Bonilla. Johan Santana was drafted by the Marlins, but that was only in a pre-arranged swap of picks with the Twins. And Josh Hamilton played only a year for the Reds, yet that in turn was only because the Reds were able to buy him from the Cubs, who had selected him in the Rule 5 Draft.
Only 14 players have amassed 2 WAR the year after they were taken. Doug Corbett picked up a whopping 5.9 WAR. Ted Abernathy, 10 years into his Major League career, was somehow a Rule 5 pick, and he quickly had the best year of his career at 5.6 WAR, finishing 20th in MVP voting. After that, the familiar faces of Joakim Soria, Dan Uggla, and Josh Hamilton made the most immediate impacts. 14 players have been drafted twice, and Shane Victorino is the most successful.
The Twins have been the best drafters, and that doesn't even count their trade for Santana. Minnesota was the team that got that value out of Corbett, and the Twins also sapped all the talent out of Shane Mack after selecting him in December of 1989, which you can see from the table below.
The Pirates have seemingly been pillaged by the Rule 5 draft, but again, they were able to reclaim Bonilla, which offsets some of their losses. The real question is, why didn't the Pirates protect Bonilla in the first place? They took another hit when they let Bip Roberts go. The Pirates had drafted Roberts twice, and were able to sign him when they used their first-round pick on him the second time, but he was plucked clean by the Padres, and went on to develop into a nice player. The Diamondbacks, in their short time, have only had a handful of players taken from them, but those include Dan Uggla and Luis Ayala.
The Giants and Red Sox have made about 20 Rule 5 picks each, and have had 0 pan out as players, unless you want to count Javier Lopez. I don't. In fact, many teams have gotten no return from the Rule 5.
Evaluating a Rule 5 pick is in parts straightforward. The drafted player will make the league minimum salary. $50,000 per selection is $50,000. The tricky part is how much value to place on losing the flexibility of a 40-man roster spot. Most Rule 5 picks never become more than replacement level, especially not in that first year when they're guaranteed a roster spot. I'd say that five players a year are, or become, better than replacement level, while 15 picks are made per year. So if a team covets a player, using a Rule 5 pick on him can be worth the while, but 10 picks in, teams are just as well off passing on their selections, which they often do. I don't see any hidden value in the Rule 5 Draft. I struggle to even see the purpose of this outdated draft model. A boring draft makes for boring analysis.