tilts head I didn't battle specific pokemon (even at Le Wow you can't choose), but in EV training I didn't plan to focus on more than 2 specific stats for each mon.
If you did lewow twice for your levels, that's 30 monsters… if you did lewow three times, that's 45 monsters... and each one of those mons would have given you 1-3 points in an ev. Specific and consistent to the monster, but not specific to your training.
Then that means you've probably already got 40-70 evs AT LEAST distributed into random stuff. Some of that will be the stats you want, but the rest is just garbage eating your potential. And if you did lewow more than that, or other mons before that, even more so.
Basically, by leveling first, you've probably consumed 1/3 or more of your potential evs in places you dont want them to go. You might still be able to max out a stat, but theres no way you'll get the full potential of 2... and you almost certainly are wasting some completely in an attack/special attack split.
(Having random points in hp or defenses isn't too bad, but...)