If you take A-Rod and Griffey out of it as two once-a-generation talents drafted #1, it gets worse. Even if you include players like Asdrubal Cabrera, Shin-soo Choo and Adam Jones in Seattle's tally of drafted players they are STILL one of the 2 worst teams in the majors at adding talent through the draft. Seattle's problem is two-fold: they do not develop much talent and when they do they give it away.
Name me the 4th-best hitter ever to come through the Mariners' system and stay a while (the first 3 are Gar, A-Rod and obviously Griffey). His name is Kyle Seager. 5th is Alvin Davis. 6th is Bret Boone, but we traded him and he came back (same with Raul Ibanez). Harold Reynolds is on that list... but the list is sparse.
Pitching? After the King on the Seattle-only-WAR chart comes Langston, then the Chief Freddy Garcia, then Mike Moore of the 95 career ERA+. Eric Hanson was decent, so there's that - and Joel Pineiro is 6th ALL-TIME with 9 WAR in a Mariners uniform from a Seattle-drafted player.
It's great to trade for Jean Segura, but have you seen Chris Taylor's 140 OPS+ for the Dodgers? Gave that guy away for nothing. Those are the throwaway trades that make it hard for the Mariners to gain ground even when they have trade successes. Whenever the Mariners gear up to trade a James Paxton or Kyle Lewis I twitch reflexively, like Nurse Ratched is coming back with the shock therapy. If you are the worst-drafting team in the league AND you trade your only decent draftees (a Choo / As-Cab / Adam Jones / Doug Fister type squad would be second only to the HOFers on those lists) it puts you in a bind.
You can deal with that one of two ways: better identify which talents you should be keeping so you don't throw away 30 WAR players for two months of 1/2 of a platoon... or just trade everyone, assuming that you are a terrible drafter and you might as well take on someone else's players. That still requires talent evaluation, though.
The Mariners have had GMs who think the guy before them did nothing right, and so they have thrown the baby out with the bathwater to a large extent. The Yankees are also terrible drafters, but they held on to Posada and Jeter and Cano as they came through the minors, correctly identifying them as talents. They then trade the rest of their junk, knowing they can pay a lot to retain talent. The Mariners haven't ponied up the money and have been miserable judges of their own talent. For me, O'Neill-for-Marco is just the latest example of that. I fully expect O'Neill to now get the instruction he needs and to turn into a Matt Carpenter for the Cardinals. They are good at that sort of thing, while the Ms are not.
As it stands, I hope for the back-end pitchers to punch above their weight so we can compete the rest of this year and next before the old heads on the roster fall apart. Realistically though, I expect the Mariners to squander this batch of hall of fame talents the way they did their last couple of sets.
It's a Mariner tradition. At least we also get to watch fun players as we flop around outside the playoffs though. The Mariners may be terrible but they find ways not to be completely boring. See you in 2 years, Kyle Lewis, and eagerly await you continuing the fun player tradition.