In sports parlance, Bob Costas remains day-to-day for NBC.

The longtime NBC Olympics host continues to be sidelined due to an eye infection that has left him “very frustrated,” according to of Mark Lazarus, chairman of NBC Sports Group. Lazarus spoke with reporters in a conference call on Wednesday, primarily to tout the impressive ratings performance of these Games, but the subject of Costas was addressed early on.

“I am not surprised it has got this much attention,” said Lazarus. “Bob is America’s Olympic host. They’ve come to expect him being here. When he’s not, it’s a story. We’re taking it day-by-day, and we hope that Bob will be back in the chair soon.”

Costas was to be replaced as Olympics host for a second straight night Wednesday by Matt Lauer of “Today.” Lazarus said Costas was being treated by Russian doctors but offered few other details.

Overall, NBC’s average primetime viewership through Tuesday (25.9 million) is nearly equal that of Vancouver from four years ago (26.4 million) — an impressive feat given that much more of the action from Canada was live — and well ahead of Torino in 2006 (21.6 million).  The time difference from Sochi to New York is nine hours, but that hasn’t been a big factor.

“For most viewers, it just doesn’t matter,” said NBCUniversal’s president of research Alan Wurtzel, who was also on the conference call. “The headline of this Olympics is that our multi-platform and network strategy has clearly resonated.

“We learned in London that the more devices they (viewers) used to consume the Olympics, the more time they watched the Olympics and primetime viewing only went up. This cross-platform viewing is really what the future is going to be. We’re not myopic… we have to be broader than that.”

The decision to put 12 hours of live coverage on NBC Sports Network has resulted in record ratings for the cabler. It averaged a best-ever 1.1 million viewers for the 6 a.m.- 3 p.m. ET time period on Tuesday. NBCSN set weekend daytime records for its live Sochi Olympic telecasts on Saturday and Sunday.

NBC Olympics’ three digital platforms (NBCOlympics.com; NBC Sports Live Extra app; an the new NBC Olympics Highlights and Results app) have drawn nearly 30 million viewers through Tuesday — up 54% from the 2010 Vancouver Games. Nearly 600,000 viewers live-streamed Shaun White’s performance on Monday, making it the second most popular event on the live stream, behind only the women’s soccer final from London in 2012.