he's one of the top 5 or so best pitchers under 30 and the numbers are closer enough between all of them that whoever has the most longevity is probably going to go down as one of the best ever. The 10-15% chance that it ends up being strasburg is pretty decent
1. Strasburg has 26 WAR, Kershaw has 57.
2. Strasburg ranks 128th on the list of career WAR through his age-28 season among pitchers. It's not exactly like he was a "late bloomer" - he was maybe the most hyped pitcher of all time.
3. To be a top-25 all-time pitcher, Strasburg needs about 75 WAR, or about 50 WAR more. There are only 20 pitchers in history who have put up 50 WAR starting in the age-29 season.
Quite simply, it's a homer argument. Perhaps the MOST homer of arguments. If you put up simple WAR totals, Strasburg's career is far more similar to Gio Gonzalez than Clayton Kershaw. Now you may say, "that's just because he hasn't been healthy, his ratios are great" but the answer to that is, health is a skill for pitchers.