I'm weighing factors such as age relative to league level, success already experienced, defensive position, and reputation among scouts.
With apologies to Chris Wallace, Tanner Bushue, Mike Kvasnicka, Telvin Nash, Jay Austin, and others, here are 9 prospects who could legitimately carry the title of the Astros' top prospect, post-Lyles (after the jump):
9. J. D. Martinez - He's an exciting hitter, with a consistently high average, solid plate discipline, and decent power, but the margin of error is small, since he is the oldest prospect on this list and seems limited to the corner outfield or 1B long term. It would be nice to see some additional HR power this year, but the doubles were really falling before he was sidelined by a minor injury.
8. Austin Wates - His chance to be an impact player is a lot higher if he can stick at CF. His bat could be a strength at that position, but much less so at one of the corners. Wates has been consistent this year but has not excelled in any one area as a hitter. He has no obvious weak point either though. He turns 23 in September.
7. Jose Altuve - On results alone, Altuve would arguably be at the top of the list. He has succeeded at every level and is still only 21. He mixes moderate power and solid plate discipline with good contact rates and good speed. The lingering question is about his size (in the 5'5''-5'6'' range). Nothing has stopped him yet though, and he is off to a strong start at AA after his promotion earlier this week.
6. Jio Mier - Mier has rebounded some from a disappointing first full season. He is repeating A level ball at Lexington, showing good patience and respectable power. He needs to cut down strikeouts, but doesn't have to be a great hitter to still yield significant value at a premium position in the future. He projects to be a shortstop long-term, and he turns 21 later this season.
5. Jonathan Villar - As is the case with Mier, much of his potential upside is tied to his position as a shortstop. Though his results were mixed this year at high-A Lancaster, the Astros were impressed enough to promote him to AA alongside Altuve. One national publication had him in their top 100 prospect list (barely) at the beginning of the season, so his skills, though raw, have attracted notice. He still also very young (just turned 20!), so he has a long time to iron out significant holes in his game (high strikeouts, erratic fielding).
4. Mike Foltynewicz - This young pitcher is well-thought of by some national prospect trackers (John Sickels comes to mind). He has yet to see consistent results this year at single A Lexington (especially concerning is the pedestrian strikeout to walk ratio), but he still probably gets the nod as the pitcher in the system with the highest upside. Youth plays in his favor as well (turns 20 in October).
3. Delino DeShields, Jr. - His selection in the first round of the 2010 draft was not well received by some Astros fans, and his output this year has done little to change the perception that he was an overdraft. In his favor though, he has shown some pop in his bat, and he is still very young (DOB: 8-16-92). The hope is that he will cut down on baserunning errors and strikeouts as he matures.
2. Ariel Ovando - Could a guy who has yet to play for an Astros minor league team really be considered our top prospect, post-Lyles? One of the advantages Ovando has in this race is that his weaknesses have not been put on display like those of the other candidates! His ceiling as a hitter is considered to be high, so as the short seasons get under way, Ovando will be watched closely to see if he can deliver on some of the hype. Even with a good start though, he will have a long road until he reaches the majors.
1. The player the Astros draft next week with the #11 pick in round one - This player-to-be-named-later has a good chance of carrying the mantle of top prospect in the Astros' system, post-Lyles. An easy test is to ask, "Would we want to draft any of the guys listed above with the number 11 pick this year?" I suspect that in a deep draft such as this one, the answer would be "no" (though Ovando might be tempting). So when you hear his name called next week, you are probably hearing the name of our new #1 prospect.