I think if you go back and look at each pick and then compare how they've done relative to their draft slot in the draft they were taken at, you'll find that Danny has returned pretty positive value out of the draft.
Yes, there have been some misses. Fab Melo and JaJuan Johnson didn't return a lot of value.
But there have been a lot of very clear successes.
2006 Rondo was picked at #21 but has returned the 5th most Win Shares of his draft class. In that same draft, Danny traded also for #49 pick Leon Powe who despite only playing just 5 years STILL is ranked 18th in Win Shares for that draft class.
2007 The next year, he traded #5 pick Jeff Green for Ray Allen. That's a huge return out of the draft. Okay, that's not in the 10+ range being discussed, but along with Ray he also got #35 pick Glen Davis. Davis went on to accrue the 21st most Win Shares of his draft class, and that was in only 8 seasons.
2008 Giddens at #30 returned the typical return of his draft slot: Pretty much nothing.
2010 Avery Bradley, picked at #19, has accrued the 15th most Win Shares of his draft class -- and was MUCH higher up the rankings during his career in green.
2011 The aforementioned JJJ was, in hindsight, not a good pick. Though Danny also picked E'Twaun Moore out of that draft at #55, who has gone on to have a very solid career in the NBA, currently ranked 23rd in WS for that class.
2012 Okay, sure, Fab was a bust. But Sullinger at 21, for the 5 years he was in the NBA returned 15.3 Win Shares and while he was with Boston was clearly one of the top 10 players out of that draft ... yes, he couldn't stay conditioned and is now eating rice balls in China. But we got a heck of a lot of value out of that pick.
2013 Everybody complains that he took Olynyk (13) instead of Giannis. Fine. But regardless, Olynyk was still a solid pick and has gone on to accrue the 7th most Win Shares of that draft class. Again, we got a lot of value out of that pick.
2014 James Young at #17. Sigh. I'm convinced to this day that Danny really wanted Nurkic, who was taken at #16. It's hard to expect much of anything out of a #17 pick but yeah, Young was probably a bust. Sad. He would show flashes and then ... do nothing.
2015 RJ Hunter (#28) and Mickey (#33) ended up as worth less than their draft slots. But Rozier (#16) ended up being hugely valuable through his 3rd year, especially if you add in playoff Win Shares. And even with his not-so-fun last season, he's still ranked 13th in regular season WS for his class and perhaps more importantly, proved very valuable as a salary in trade to help bring in Kemba. As a probable starter for Charlotte, he'll likely accrue excess value for a #16 pick.
2016 After Jaylen at #3, this draft was a case of too-many-picks. Danny picked for stash (Yabu and Zizic) and traded away #31 & #35. None has returned much value. Yabusele was on track to be an 'average' #16 pick after his first season, but then did nothing last year. Zizic (#23) actually started to return decent value last year for CLE and probably will carve out a career as a journeyman big in the NBA. He's currently ranked #21 in WS for that class. The trades of #31 & #35 yielded the pick that was used to take Matisse Thybulle who was then traded for what became Carsen Edwards and another pick.
For more recent drafts, I think is too recent to really evaluate, though I think the end results on the last three drafts will prove pretty positive.
So there have actually been quite a few players that Danny has picked outside of the top 10 that have provided a lot of value -- especially to the Celtics -- above their draft slot. And in some cases, Danny has been able to extract value out of the draft via trade when the player choices at slot weren't necessarily great.
Ultimately, the Cs have gotten to the playoffs 14 of 17 seasons since Danny took over. That includes 5 trips to the Conference Finals or higher. That has meant that most draft picks he's had (other than those he's acquired in trade) have been on the bottom half of the first round or later. I personally don't see a lot of reason to complain.