He’s on a 10 WAR pace this season with an OPS over 1000. Do players who perform like this at a very young age actually improve? What do their aging curves look like?

I though I’d look at some young players who made a big splash at a young age to see what their careers had in store for them.

Mike Trout announced himself to the league at age 20 with 10 WAR. His offense did follow a traditional growth pattern to age 27 (and he seems to be at that level still), but declining defense and time lost to injuries have precluded a succession of 10 WAR seasons, though when healthy, he stills performs at that level.

Alex Rodriguez also made his splash at age 20, with a 1000 OPS and 9 WAR and more or less held steady until age 31, with a few dips en route. There was no obvious growth from his first big season. I leave it to others to debate the role PEDs played in his career.

Ken Griffey performed very well from age 20-22, but at age 23 he broke through, recording his first of four 1000 OPS seasons. The 9 WAR he posted would be matched just twice in his career, actually being exceeded during his peak at ages 26-27. His bat held steady from age 23 to 29, but his defense declined and then injuries were the story throughout his 30s.

Ted Williams established himself as Ted Williams in his rookie season at age 20. He reached his peak at age 22 and stayed there until age 28, posting one 10 WAR season after another (missing out on three likely such seasons due to military service). His decline would start at age 31. Age 38 saw his Ponce de Leon season, finding ~10 WAR one more time. So he never really improved from who he was at age 22, but he managed to stay at that level for a long time.

So what does this very brief and certainly unscientific study mean for Guerrero? Will he actually improve from age 22 (assuming he retains his 10 WAR pace)? Boy, that does seem like a very greedy thing to ask for. Trout and Griffey improved as hitters, but gave away points as their defense in CF declined. But they weren’t sporting a 200 OPS+ like Guerrero is, so had room to grow offensively. If Guerrero can model Ted Williams (yeah, just that) and sustain his current level into his late 20s, that would be a monumental achievement in and of itself. He’d go down as one of the all-time greats.

So perhaps the “Guerrero’s only going to get better” talk should be given a rest. Age 22 may in fact be his peak, and a more reasonable thing to hope for is that he can live in this stratosphere for the foreseeable future.

I was there too.  It was a weekday matinee, the only game on the docket.  And it was the morning after Angel Nick Adenhart was tragically killed by a drunk driver.

It was also the first MLB game to feature a matchup with two pitchers both drafted in the first round and both making a debut.

Porcello was among the very top players in the 2007 draft. However, he fell to the Tigers at 27th overall due to his over-slot demands. (Scott Boras was his agent.)

		ERA	GS	IP	W	L	H	R	ER	HR	BB	K	FIP	WHIP	ERA+
															
Bieber	CLE	2.36	24	156.1	14	4	111	44	41	16	50	239	2.48	1.030	189
Lynn	CWS	2.46	23	142.2	13	4	101	46	39	18	42	152	3.71	1.002	178
Cole	NYY	2.54	24	148.2	13	6	108	47	42	20	28	198	2.88	0.915	165
Ryu	TOR	2.95	23	131	10	5	120	47	43	14	28	131	3.22	1.130	146
Bassitt	OAK	2.96	23	137	10	4	116	47	45	12	34	135	3.27	1.095	135
Eovaldi	BOS	3.76	21	115	11	4	116	49	48	10	21	117	3.01	1.191	120
Glasnow	TBR	3.28	23	134.1	 9	3	 89	49	49	21	47	197	3.31	1.012	119
Greinke	HOU	3.67	25	149.2	 9	5	141	61	61	16	25	127	3.40	1.109	117

• Dave Stieb: 5 starts, 4.26 ERA 1-3 record.
• Jimmy Key: 7 games, 5 starts, 3.03 ERA team was 4-3 in those games.
• Juan Guzmán: 8 starts, team 7-1, 2.44 ERA - all in his first 3 ML seasons. The loss was a 2-0 loss.
• David Cone: 4 starts, 3.22 ERA team 3-1, twice didn't get through 5 innings
• Pat Hentgen: 2 starts, 1-1 record, 7 ERA, both in 1993 - was scheduled to start game 7 if not for the Carter home run. We were all scared of it.
• Tom Candiotti: 2 starts, 8.22 ERA Ugh.
• Mike Flanagan: 1 start 5 R in 4 1/3 IP, a loss.
• R.A. Dickey: 2 starts, 7.11 ERA, team 1-1 in his starts.
• David Price: 4 games, 3 starts, 6.17 ERA, team 1-3.
• Marcus Stroman: 5 starts, 4.40 ERA team 3-2.
• Dave Stewart: 4 starts, 4.26 ERA, team 3-1.

• Babe Ruth: 3 starts, 97-78-54 (8 IP 2 R)
• Bob Gibson: 9 starts, 93-87-82-81-80-80-62-56-55. 8 IP once, 9 7 times, 10 once. Crazy.
• Sandy Koufax: 7 starts, 1 relief. 88-88-79-79-68-62-50
• Whitey Ford: 22 starts, 88-81...28-28. 7 scores sub 50, once only lasted 1 inning.
• Greg Maddux: 30 starts, 5 relief, 83 peak, 16 worst
• Randy Johnson: 16 starts, 3 relief, 91 peak twice (2001 9 IP 1 BB 11 SO 3 H shutout, 2001 WS same line), 5 sub 50's worst a 23 in 2005 as a Yankee
• Curt Schilling: 19 starts, 89 peak (80 vs Jays was his 3rd best), worst a 22 as a Red Sox.
• Christy Mathewson: 11 starts, peak of 86, worst a 45, his only sub 60.
• Mordecai Brown: 9 starts, peak of 86

The eye test suggests that a Bichette who is just a wee bit more selective could produce a whole lot more. But he's only 23 and yet to accrue even a full season's worth of at-bats. Plenty of time for progress.