A Jason Heyward Comp: Jeff Bagwell? Nobody?

It’s obvious that Jason Heyward’s .277/.393/.456 debut was impressive, especially since it came at the tender age of 20. When it comes to his walks, it was just a hair short of record-breaking. His 91 walks last year were the the third most walks in a debut since 1960. Heyward will obviously be a boon to his team if only for that great walk rate, but are there are any other players that broke in with similar plate discipline stats that can show us a similar debut and can therefore tell us something about Heyward’s possible future development path? Or is Heyward unique?

Well, there is a player in the news right now that might just be somewhat comparable: Jeff Bagwell. Bagwell may have to wait to get into the Hall, but he debuted with 75 walks at 23 years old. That’s the most walks in a rookie season put forward by a player younger than 23 since 1985 (other than Heyward’s of course). We also know, with the benefit of hindsight, that walks would feature greatly in his game going forward, as he steadily upped his contribution in the category from 75 to a peak of 149 in 1999. His plate discipline came well-formed and was refined over time, and the similarity seems to suggest that Heyward will have many .400+ OBPs – Bagwell had seven, with two more over .397.

But what might a Bagwell comp mean for Heyward’s power? Bags famously wielded a light stick in the minor leagues (he hit only eight home runs in 212 minor league games, with a .436 SLG and a .115 ISO), but in his major league debut, he hit 15 home runs and showed a .437 slugging (.143 ISO). Heyward hit 29 home runs in 238 minor league games (.508 SLG, .190 ISO), and debuted with 18 home runs, a .456 SLG, and a .179 ISO. These aren’t perfect comps here, but Heyward won’t complain if he ends up with Bagwellian power eventually.

Braves fans in the projections, however, seem to expect the power to arrive more quickly than this comp would suggest it’s coming. Bagwell hit 449 home runs, but he hit only 53 in his first three seasons. In that 1994 season, his age 26 season, he finally broke out with 39 home runs. Look at the Bill James projection for Heyward this year, and you see a muted projection of 22 home runs and a .198 ISO (19 extra ISO points) that would look about right next to Bagwell’s sophomore debut in which he added 28 points of ISO and hit 18 home runs.

There is another player on the walk list that I want to bring up: Ike Davis walked 72 times in his debut, and no-one is talking about him as a comparable player to Heyward. And 72 is much closer to 75 than 75 is to 91. Davis also suffers from not having a minor league record that looks like Heyward’s – he only showed a .179 ISO in the minor leagues. Wait, is Bagwell a comp for Davis? I digress.

We do still have Heyward’s minor league dominance to take into consideration. Curt Blefary isn’t a name that will jog many memories, but he came up in 1965 (at 21) and walked 88 times against 73 strikeouts with 22 home runs (and had a .499 minor league slugging percentage), so in some ways he’s an interesting comp. But his .470 debut slugging percentage hid a .210 ISO, making his rookie season more powerful than Heyward’s, and he hit 31 home runs in Double-A before coming up. Of course, Blefary never slugged as high again in his career and was done at 28, and despite winning the Rookie of the Year award, he didn’t have the hype or the batting average of Heyward coming up, either (.270 minor league BA, .232 major league BA).

Alvin Davis, a first baseman that came up in 1984 in the Seattle organization, is somewhat similar. He burned through the minor leagues quickly (206 games in two years), had a decent slugging percentage (.497, .203 ISO), and walked 173 times against 95 strikeouts. In his rookie year, he walked 97 times to Heyward’s 91, but he hit 27 home runs and had a .210 ISO that year, too, so he showed more power in his debut. He was also 23 that year, three years older than Heyward. Albert Pujols, who walked 93 times and hit 37 home runs (with a .281 ISO), also is too overpowered to be a comp.

Sort the list for OBP, and it’s about the same, although Austin Kearns zooms to the top. That .370 BABIP in his rookie season had a lot to do with his OBP, but the 22-year-old Kearns had a nicer debut than people might remember and should be considered as a comp, if ultimately discarded for his lack of a strong minor league record. Sort the list for walk rate, and you’ll still get the same players near the top (Blefary, Hayward, Davis in order), but Barry Bonds and his 13.4% walk rate in his debut shows up. His .416 SLG in his debut seems to exclude him from the list, but he had a poor batting average that year and actually had a .193 ISO. He also stole 36 bases, though, and was seemingly a different player based on his speed and defense. If we use Bonds as a comp for Heyward’s power, though, we end up in a similar place as we did with using Bagwell as a comp – Bonds’ ISO hovered around .200 for a while, and he didn’t crack 30 home runs until 1990, when he was 26.

There just aren’t many comps for Heyward’s debut. He showed extremely good plate discipline and yet ‘only’ above-average power at a young age. He may age like Ken Griffey, Jr – another young rookie – but he also walked almost twice as often as Griffey in his rookie year. He may age like Bagwell, in which case we’ll see some great power years in his peak, but not right away. He may age like Bonds and show similar muted power until he bulks up in his mid-to-late 20s.

Or maybe he’ll simply age like Jason Heyward.