Josh Giddey has the most career boards by a guard younger than 22, with 1,534 boards.

Interpreted as:

most career rebounds by a guard before turning 22 years old

NAME	REB	GP	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	AST	STL	BLK	TOV	PF	+/-
Josh Giddey	1,534	210	28.9	13.9	7.3	5.7	0.8	0.5	2.6	5.8	12.5	46.4	1.0	3.3	31.0	1.2	1.7	75.3	6,079	2,920	1,200	159	95	550	342	-29
Luka Doncic	1,395	164	33.2	25.4	8.5	7.6	1.0	0.4	3.9	8.5	18.8	45.2	2.6	7.8	32.7	5.9	7.9	74.2	5,453	4,168	1,245	171	61	636	354	+157
Anthony Edwards	1,137	223	34.2	21.8	5.1	3.7	1.4	0.6	2.7	7.9	17.9	44.1	2.7	7.6	35.2	3.4	4.4	77.0	7,622	4,871	836	312	140	609	479	+57
RJ Barrett	1,101	198	33.5	17.5	5.6	2.9	0.8	0.3	2.1	6.3	15.1	41.8	1.6	4.6	35.7	3.3	4.7	69.7	6,633	3,469	568	151	53	414	452	-334
Kobe Bryant	1,054	266	28.5	15.9	4.0	3.0	1.1	0.7	2.3	5.6	12.4	45.0	0.7	2.3	33.1	4.0	5.0	81.6	7,579	4,240	803	301	175	608	655	+947
LaMelo Ball	1,034	162	31.8	19.4	6.4	7.3	1.5	0.4	3.2	7.0	16.3	42.6	2.8	7.5	37.7	2.7	3.3	82.8	5,158	3,149	1,188	246	59	519	491	-135
Tracy McGrady	858	126	33.3	20.0	6.8	3.7	1.3	1.5	2.2	7.6	16.7	45.3	0.5	1.6	33.3	4.3	5.9	73.1	4,193	2,523	465	168	184	278	254	+223
Russell Westbrook	844	171	33.6	16.0	4.9	6.7	1.4	0.3	3.3	5.7	13.9	41.0	0.3	1.4	24.1	4.3	5.3	80.5	5,748	2,736	1,142	233	54	570	417	-6
Jalen Green	746	193	32.5	19.5	3.9	3.2	0.7	0.3	2.3	6.7	15.9	41.9	2.3	6.9	33.5	3.8	4.8	79.4	6,280	3,759	621	138	52	443	301	-989
Jrue Holiday	735	220	31.2	11.9	3.3	5.0	1.4	0.3	2.3	4.7	10.7	44.0	0.9	2.5	37.7	1.5	1.9	79.8	6,864	2,611	1,101	302	65	509	493	+229
Larry Hughes	735	166	27.9	13.7	4.4	2.7	1.4	0.4	2.3	5.1	12.8	39.7	0.3	1.4	21.2	3.2	4.3	74.2	4,627	2,268	446	229	66	375	398	-491
Jamal Murray	732	215	28.2	14.4	3.4	3.3	0.8	0.3	1.9	5.3	12.2	43.1	1.8	4.9	36.1	2.2	2.4	88.2	6,073	3,106	702	174	72	408	407	+476
Bradley Beal	725	192	33.2	15.6	3.8	3.0	1.0	0.3	1.8	5.9	14.0	41.9	1.7	4.4	40.0	2.1	2.7	78.6	6,382	2,991	574	197	65	341	402	+215
Andre Iguodala	718	124	34.6	10.0	5.8	2.9	1.6	0.5	1.7	3.6	7.2	49.9	0.6	1.7	35.1	2.3	3.1	74.0	4,286	1,244	357	199	61	208	315	+44
Devin Booker	698	212	32.3	20.0	3.3	3.5	0.8	0.3	2.9	6.9	16.1	42.8	1.9	5.2	36.5	4.2	5.0	84.8	6,840	4,231	748	166	55	617	650	-976
Chris Paul	680	142	36.3	16.6	4.8	8.3	2.1	0.1	2.4	5.5	12.8	43.3	0.7	2.3	31.3	4.8	5.8	83.5	5,161	2,362	1,180	293	9	344	372	-226
Tyler Herro	677	147	29.9	15.9	4.6	3.1	0.6	0.2	2.0	5.9	13.6	43.2	2.2	5.8	37.9	2.0	2.3	84.9	4,393	2,344	458	93	32	294	201	-14
Ben Simmons	659	81	33.7	15.8	8.1	8.2	1.7	0.9	3.4	6.7	12.3	54.5	0.0	0.1	0.0	2.4	4.2	56.0	2,732	1,279	661	140	70	278	211	+387
Tyreke Evans	655	129	37.1	19.1	5.1	5.7	1.5	0.4	3.1	7.1	16.3	43.6	0.6	2.2	27.3	4.3	5.7	75.6	4,784	2,462	733	194	56	400	347	-533
Tony Parker	650	234	32.6	13.1	2.8	5.0	0.9	0.1	2.3	5.0	11.2	44.7	0.9	2.7	32.5	2.2	3.1	71.7	7,618	3,073	1,177	221	18	528	488	+1021
Kyrie Irving	636	174	33.8	20.8	3.7	5.9	1.3	0.4	3.0	7.6	17.0	44.7	1.7	4.5	38.3	3.9	4.6	86.0	5,880	3,623	1,024	232	62	526	406	-551
Coby White	630	172	28.4	14.0	3.7	3.5	0.6	0.2	1.8	5.1	12.2	41.4	2.2	6.1	36.4	1.7	2.0	84.8	4,891	2,415	607	106	31	313	384	-285
Lonzo Ball	627	102	32.3	10.1	6.1	6.4	1.6	0.6	2.4	3.9	10.4	38.1	1.7	5.4	31.8	0.5	1.2	44.8	3,296	1,034	651	162	62	242	238	-66
John Wall	617	135	37.0	16.3	4.6	8.2	1.6	0.7	3.8	5.7	13.8	41.6	0.3	1.2	23.6	4.6	5.9	77.7	4,992	2,207	1,104	216	92	516	312	-696
Shai Gilgeous-Alexander	616	145	30.3	14.5	4.2	3.3	1.1	0.6	1.8	5.4	11.4	47.4	0.9	2.5	35.7	2.8	3.5	80.1	4,388	2,105	478	166	90	258	283	+40