Excited to see the 49ers’ high-end draft picks put them over the top in 2014?

Here’s some cold water, courtesy of ESPN’s Bill Polian.

On a national conference call today, the legendary former NFL personnel executive said, rather emphatically, first- and second-round picks rarely become difference-makers as rookies.

“The first and second rounder, you would like them to come in and contribute,” Polian said. “And let me underline the word contribute, please. They will not make an impact. They will not. Rookies cannot make an impact. By the very definition of the fact that they are rookies. They have to learn how to play professional football … We assume these guys are going to come in and make the difference between winning and losing. And they rarely, rarely do.”

The 49ers have a first-round pick and two second-round selections. Should we assume those picks are destined to, at best, achieve mere contributor status this season? With proper respect to Mr. Polian: of course not.

There are obviously plenty of exceptions to Polian’s they-will-not-make-an-impact statement. In fact, just examine the 49ers’ first- and second-round picks since 2010: Four of the five first-rounders made a significant impact in their first season:

2010

First round: RT Anthony Davis (No. 11)

Difference-maker: started 16 games; played 1,011 of 1,013 offensive snaps

First round: LG Mike Iupati (No. 17)

Difference-maker: started 16 games; played 983 of 1,013 offensive snaps

Second round: S Taylor Mays (No. 49)

Contributor: started six games; had 26 tackles, recovered blocked punt in end zone for TD

2011

First round: OLB Aldon Smith (No. 7)

Difference-maker: ranked fifth in the NFL in sacks (14)

Second round: QB Colin Kaepernick (No. 36)

Non-factor: played 20 snaps; completed 3 of 5 passes for 35 yards

2012

First round: WR A.J. Jenkins (No. 30)

Non-factor: had zero catches in three games

Second round: RB LaMichael James (No. 61)

Contributor: had 38 carries, 190 yards and TD (including playoffs); averaged 27.6 yard on 21 kickoff returns

2013

First round: S Eric Reid (No. 18)

Difference-maker: started 16 games; ranked third on team in tackles (77), second in INTs (4); went to Pro Bowl as alternate

Second round: DE Tank Carradine (No. 40)

Non-factor: did not play because of a knee injury

Second round: TE Vance McDonald (No. 55)

Contributor: had 8 catches for 119 yards in 15 games; played 494 snaps