Analysts weren't surprised when news came out earlier this week that AmSurg (AMSG) was pursuing a deal with Envision Healthcare Holdings (EVHC) . But what did perturb at least one analyst was why Envision would be interested in combining with AmSurg in the first place.

"What is most surprising to us is that EVHC would be interested in a deal with AMSG," KeyBanc Capital Markets analyst Jason Gurda wrote in a Thursday. "While EVHC shares are well off their 52-week high, we believe it would be difficult for the Company to obtain a significant premium to its current price without the deal being dilutive, which could negatively impact AMSG's share price."

The Wall Street Journal, citing unnamed sources, reported Wednesday afternoon that the companies are in advanced talks and a deal could materialize as soon as next week.

For AmSurg, an outsourced physician services company, the company seems desperate to capture growth via a larger deal. Last year AmSurg offered to combine with hospital staffing company TeamHealth Holdings (TMH) , a proposal that was rebuffed. AmsSurg withdrew its proposal in November. The failed courtship followed a consummated 2014 deal for Sheridan Healthcare that cost Amsurg about $2.35 billion in cash and stock.

AmSurg had net revenues of $2.57 billion in 2015, up 58% from $1.62 billion in 2014.

For Envision, whose stock traded as high as $45.95 on Aug. 4, the motivations are not so apparent.

"While EVHC shares are well off their 52-week high, we believe it would be difficult for the Company to obtain a significant premium to its current price without the deal being dilutive," KeyBanc's Gurda wrote.

He said the deal may have been leaked to the press to give Envision "increased leverage in negotiating what percentage of the combined company it will receive."

In a Wednesday note, Canaccord Genuity analyst Richard Close said, however that Envision's stock as undervalued at present levels. In early afternoon trading on Friday, Envision shares were changing hands at $27.58, down 0.83%, and AmSurg shares were trading at $80, down 1.2%.

Envision seems to be operating from a position of strength, having increased net revenues from $4.4 billion in 2014 to $5.45 billion in 2015. Envision's fast growing Evolution Health platform "is expected to double revenue in coming years due to the increasing importance of care transition from in-patient to post-acute settings," Close said. Evolution Health is part of Envision's Emcare physician-led facility-based and post-acute care services segment, which had net revenue of $3.65 billion in 2015, up from $2.84 billion in 2014.

Still, a merger between Greenwood Village, Colo.-based Envision and Nashville, Tenn.-based AmSurg "would be notable, combining the largest medical transportation and physician and clinical management services operator in Envision with the leading ambulatory surgery center company with an already strong presence in clinical management/physician services," Close wrote.

An AmSurg representative said the company does not comment on market rumors. An Envision representative was not immediately available on for comment.

Envision last year acquired nine companies for total consideration of around $1.4 billion, according to its 10-K filing. That includes the $620 million purchase of Rural/Metro Corp., which was completed in October. This year, Envision acquired Emergency Physicians Medical Group for $120 million, plus a contingent consideration based on the target's future performance.