Some people worry about Hamilton's past drug abuse and how much that may have aged his body. However, there are some important on-the-field concerns too.
Hamilton's skillset is interesting and problematic. He is basically an average (at best) outfielder with a prodigious power bat but a violent approach at the plate. He doesn't walk much, strikes out a bunch, but crushes the ball when he makes contact. Hamilton has been very productive with this skillset, but once his power goes, so does most of his value.
My gut told me that a player with Josh Hamilton's skillset, at 31 years old, is not a good long-term investment. I wondered if I could find some historical comparison I could make to support or refute my gut though.
I went to Fangraphs and looked at the statistics for all players from age 30 to 31 (Hamilton is 31 years old now). In that time, Hamilton accumulated an 8.4% walk rate (aggressive), 21.6% strikeout rate (swings and misses alot), with a .267 ISO (hits the ball hard when he makes contact). Only 3 other players in MLB history, in their age 30-31 seasons, have walk rates under 10%, strikeout rates over 20%, and an ISO over .250. Here they are:
- Alfonso Soriano: Soriano is still an active player, of course, but his age 31 season was in 2007. It was his first year with the Cubs, and he batted .299 with 33 home runs, yet lots of strikeouts with few walks. Soriano signed a massive deal with Chicago, and it has often been criticized because Soriano's production trailed off. However, Soriano has maintained 25-ish home run power through his mid-30s, and while he is not a star anymore, he is still a serviceable starter. Fangraphs estimates Soriano has been worth $55.6 million over his 5 seasons since turning 31 years old.
- Frank Howard: Howard is a bit of a blast from the past, and an intriguing comparison. His age 31 season was in the famed 1968 season, "the year of the pitcher." Howard slugged 44 home runs, and hit over 40 home runs in 1969 and 1970 as well. However, Howard's power declined sharply in 1971, and he was a part-time player after that. His last year in Major League Baseball was 1973 at 36 years old. One very important thing to note about Howard is that his walk rate skyrocketed after 1968. He walked 54 times as a 31-year-old, but then 102 times and 132 times the next two seasons! Howard developed a shocking amount of plate discipline out of nowhere that helped him maintain his value, yet he was still done as an everyday player just 3 years after this age 31 season.
- Tony Armas: You might remember a pitcher by the same name, and he turns out to be Armas's son. Armas is maybe the most extreme example of a power-hitter. He hit 251 home runs in his career with a career .287 on-base percentage! Armas maintained his power stroke after turning 31, but couldn't stay on the field. He only had two more seasons where he played more than 120 games, and he was done after his age 35 season.
If I lower the ISO threshold to .240, there is another player that shows up as a Hamilton comp:
- Mo Vaughn: Mo's age 31 season was in 1999, his first season with the Angels after an illustrious start to his career with the Red Sox. Vaughn was productive (33 home runs, .866 OPS), and had another productive season at 32 years old, but then he suffered a massive injury that cost him his entire age 33 season. Vaughn was traded to the Mets, put up a decent season at 34 years old, but was washed up at 35. He never really recovered from the injury.
Put it this way: nobody that compares to Josh Hamilton as a hitter at 31 years old turned out to be worth $175 million over the next 7 years of their career. Nobody was even worth $100 million over 5 years. Hamilton would have to be a ton better than any of these comps I came up with to justify a big contract. He very well could be, but I wouldn't spend $100 million to find out.